Edit: October 3, 2015 An article in IT World for September 29, 2015 reveals the existence of, but doesn't describe fully, two serious flaws in the Windows driver that TrueCrypt installed. It isn't clear from the article whether those flaws compromise the crypto or the underlying Windows OS, or both. It also isn't clear whether that driver is installed only for full-disk encryption or at any time a TrueCrypt volume is in use.
Original answer below:
Older versions of Truecrypt are as safe as they ever were. Unhappily, the safety of older versions has not been conclusively demonstrated, I think. A code audit by others, of which phase one is complete, did not find any problems that significantly weaken the crypto algorithms, and I really doubt anyone, even the NSA, can crack AES unless there's a back door that hasn't been found. (That's a back door in Truecrypt; I'm relatively sure that AES itself is safe.)
That said, I am still trusting an older install of Truecrypt. For you to use Truecrypt, you'd have to put your hands on an old copy of the software. There is what purports to be a copy of Truecrypt 7.1 on Github. The Open Crypto Audit Project says it is verified, and I have no reason to doubt that.
There is also an open source successor, VeraCrypt, which I have not tried.