There's no harm in trying to reindex first before re-downloading the whole blockchain, so reindex first. If I remember correctly you get prompted to reindex or not if qt fails to load the block database, but if you don't get it you do that by running bitcoin-qt with -reindex command. Linux users should know how to do it.
If the files got corrupted, your hard drive may be on its end.
Let me help you check your blocks.
Do this in your blocks-directory: md5sum *.dat > checksums_for_Loyce.txt
This should be done in an hour. Post the contents here between code-tags. I'll check if any of my blocks is different. This may help you pinpoint the problem without redownloading everything.
I don't think this is necessary. You'd still end up reindexing after deleting any of the file. Also it's safer to let bitcoin-qt do its thing than deleting/replacing files by your own.