Assuming that the wallet.dat file is really yours and that you didn't bought it in the hopes of finding the password (who locks almost 3 bitcoin without noting down the password ?), I really don't see how you can achieve this. My first suggestion would be using John the ripper[1] and hascat[2] but TrueCrypt has near perfect cryptography and these tools would probably only help you in finding one or two characters at most. If the password was complex and had a mix of numbers and special characters I would say forget it but perhaps someone who is more knowledgeable in this matter will show up with a better solution than mine.
[1]
https://www.openwall.com/john/[2]
https://hashcat.net/hashcat/Yes, the file is mine. If it was not mine, how could I know the general wallet address?
Because I don't want to put the encrypted file here, I just put its hash, and whoever can decrypt the hash can find out the password.