Question: is your system partitioned into more than one partition, plus swap?
If so, the unexpected shutdown caused filesystem inconsistency in at least one partition. Enough of the system boots so that you can work from command line.
Solution: from the command line, try to mount all partitions. If a partition is already mounted, bash will tell you so. If one is not mounted and the mount command works successfully, you will get no message. That partition is the one that didn't mount on boot.
Immediately umount that partition, and run fsck on it. Then reboot to see if fsck fixed the problem.
If that fails, check /var/log/messages for errors, or run dmesg to see what turns up. Then post the errors.