Lost my BTC, though my wallet is still available Recently I have reinstalled Bitcoin qt because my HDD crashed. Fortunately I had a backup of my wallet.dat, but there is still one problem.

After the installation I replaced the wallet.dat with my old wallet.dat. If I start Bitcoin qt now, I can not see any money in my wallet?!

What can I do now?
Are you also sure that you've let Bitcoin qt fully synchronise with the network? Very recently I moved across my wallet.dat to a new installation with no issues.