Most important: your feathercoins are safe (as long as you don't delete your wallet.dat!), they are safely stored in the blockchain / network.
I'm guessing you don't have very indepth knowledge of the workings of the Feathercoin client, so here is a step by step guide to deleting the corrupted blockchain on your computer which is preventing the feathercoin client from synchronising with the network.
Do the following
- Close the Feathercoin client
- Press 'Windows key + R'
- Paste in '%APPDATA%\Feathercoin' in the run dialog that opened
- Press Enter, windows explorer will open the pasted location
- Make a copy of all files and folder located here to some other folder (just to be sure)
- Delete all files that start with 'blk' located here
- Delete the 'database' folder located here
- Open the feathercoin client
- Your client should redownload the blockchain, and sync including your transaction
Let us know how it works out.