I installed Bitcoin-QT on my machine a while ago, and I forgot my password.
So I assume the bitcoin I had in the wallet is lost, until I can remember it? (If that's not true, please somebody let me know.)
My question is:
How do I use Bitcoin-QT now on that machine (for other bitcoins I have and would transfer in.)
Can I somehow start a new wallet with a new password?
Step 1.
Make a backup of your current wallet.
Step 2.
Make sure you made a backup of your current wallet.
Step 3.
Make a second backup of your current wallet, just in case anything goes wrong with the first backup.
Step 4.
Shut down Bitcoin-Qt
Step 5.
Remove wallet.dat from the data directory (as long as you are sure that you have a good backup stored somewhere safe).
Step 6.
Start Bitcoin-Qt up again.
Step 7.
You should now have a new wallet with a new bitcoin address.