centos 6 kernel panic

Someone asked me to help him with his very slow server then I just logged in and initiated an update then I rebooted the server it couldn't start up again and gone in kernel panic on all kernels even the old one ..
I started the server in system rescue mode to try to fix the problem which I think is related to kernel update, now I can't mount all the file system the output of lsblk is

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk 
└─sda1   8:1    0   250M  0 part 
sdb      8:16   0 465.8G  0 disk 
└─sdb1   8:17   0 465.8G  0 part 
sr0     11:0    1  1024M  0 rom  
loop0    7:0    0 275.1M  0 loop /livemnt/squashfs

the output of fdisk -l

Disk /dev/sda: 465.8 GiB, 500106780160 bytes, 976771055 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x000b631a

Device    Boot Start       End Blocks  Id System
/dev/sda1 *     2048    514047 256000  83 Linux


Disk /dev/sdb: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device    Boot Start       End    Blocks  Id System
/dev/sdb1         63 976768064 488384001  83 Linux

the output of mount /dev/sda1 /mnt is successfully mount sda1 on /mnt but it's just /boot that mounting nothing else

root@sysresccd /mnt % ls
config-2.6.32-042stab113.11            lost+found
config-2.6.32-573.el6.x86_64           symvers-2.6.32-042stab113.11.gz
efi                                    symvers-2.6.32-573.el6.x86_64.gz
grub                                   System.map-2.6.32-042stab113.11
initramfs-2.6.32-042stab113.11.img     System.map-2.6.32-573.el6.x86_64
initramfs-2.6.32-573.el6.x86_64.img    vmlinuz-2.6.32-042stab113.11
initrd-2.6.32-042stab113.11kdump.img   vmlinuz-2.6.32-573.el6.x86_64
initrd-2.6.32-573.el6.x86_64kdump.img

ls /dev :
autofs           mapper              tty0   tty39  ttyS10   usbmon0
block            mcelog              tty1   tty4   ttyS11   usbmon1
bsg              md0                 tty10  tty40  ttyS12   usbmon2
btrfs-control    mem                 tty11  tty41  ttyS13   usbmon3
bus              mouse               tty12  tty42  ttyS14   usbmon4
cdrom            mqueue              tty13  tty43  ttyS15   usbmon5
char             net                 tty14  tty44  ttyS16   usbmon6
console          network_latency     tty15  tty45  ttyS17   vcs
core             network_throughput  tty16  tty46  ttyS18   vcs1
cpu              null                tty17  tty47  ttyS19   vcs12
cpu_dma_latency  nvram               tty18  tty48  ttyS2    vcs2
disk             oldmem              tty19  tty49  ttyS20   vcs3
dri              port                tty2   tty5   ttyS21   vcs4
fb0              ppp                 tty20  tty50  ttyS22   vcs5
fd               ptmx                tty21  tty51  ttyS23   vcs6
full             pts                 tty22  tty52  ttyS24   vcsa
fuse             random              tty23  tty53  ttyS25   vcsa1
hidraw0          raw                 tty24  tty54  ttyS26   vcsa12
hidraw1          rtc                 tty25  tty55  ttyS27   vcsa2
hpet             rtc0                tty26  tty56  ttyS28   vcsa3
initctl          sda                 tty27  tty57  ttyS29   vcsa4
input            sda1                tty28  tty58  ttyS3    vcsa5
kmsg             sdb                 tty29  tty59  ttyS30   vcsa6
log              sdb1                tty3   tty6   ttyS31   vga_arbiter
loop0            sg0                 tty30  tty60  ttyS4    vhost-net
loop1            sg1                 tty31  tty61  ttyS5    watchdog
loop2            sg2                 tty32  tty62  ttyS6    watchdog0
loop3            shm                 tty33  tty63  ttyS7    zero
loop4            sr0                 tty34  tty7   ttyS8
loop5            stderr              tty35  tty8   ttyS9
loop6            stdin               tty36  tty9   uhid
loop7            stdout              tty37  ttyS0  uinput
loop-control     tty                 tty38  ttyS1  urandom

root@sysresccd /mnt % mount
rootfs on / type rootfs (rw)
udev on /dev type tmpfs (rw,relatime,size=10240k,mode=755)
tmpfs on /livemnt/boot type tmpfs (rw,relatime,size=2097152k)
/dev/loop0 on /livemnt/squashfs type squashfs (ro,relatime)
tmpfs on /livemnt/memory type tmpfs (rw,relatime)
none on / type aufs (rw,noatime,si=6ab81e70f42fd0bd)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
tmpfs on /run type tmpfs (rw,nosuid,nodev,relatime,size=1643368k,mode=755)
udev on /dev type devtmpfs (rw,nosuid,relatime,size=10240k,nr_inodes=2051085,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /tmp type tmpfs (rw)
/dev/sda1 on /mnt type ext2 (rw)

root@sysresccd / % mount /dev/sdb1 /mnt     
mount: /dev/sdb1 is write-protected, mounting read-only
NTFS signature is missing.
Failed to mount '/dev/sdb1': Invalid argument
The device '/dev/sdb1' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?

You are mounting the boot partition with that mount command. Use mount /dev/sdb1 /mnt to mount the OS filesystem.

If LVM is used, the you need to do:

vgchange -a y

To activate the volume groups and LVs inside them. Then you can use lvs command to show different logical volumes on the device and then use those mount points to mount the desired filesystem.