Whenever I try to boot up linux, it says that there are problems with the root file
Based on the above statement, I don't think there is a problem with the root account, but with the root file system.
You already is root in the above scenario. When some filesystem needs manual repair, you are left in a single user mode.
You need to fix any problems in the filesystems before linux can boot in normal multi-user mode again.
The disk repair program is "fsck". It needs a filesystem path as argument. Do you know what filesystem is damaged ? The command "fdisk -l" shows all partitions in your disks. Just in case, run fsck for each device in the first column which has Id=83 ! Attention: Run fsck only in partitions of type 83. Ignore any other.
If you can, post the output of "fdisk -l", just to be sure.