Hi
I have seen this before with multibit.
Has the transaction gone through the blockchain ?
What you need to do is
1. Export your private key
2. close the open wallet
3. Create a new wallet
4. Import the private key that you just exported back into the new wallet
5. Check your balance after the sync
6. if all works and you get your money back you can send me a donation to 1Btj1wd1Gw7meVXG9qKCJXb4QFL6xa5Ucr