Recently I have migrated from ubuntu 13.04 64 bits to 32 bits in my laptop because I was getting some trouble with some software. Meanwhile, I have faced another problems with compatibility, with guitar pro 6 that I can't open after installing ( and I can made it work on ubuntu 12.04 in a virtual machine). Should I downgrade to ubuntu 12.04? Are there more programs available for ubuntu 12.04 than for 13.04?
12.04 is a long term release, supported for five years. In theory, this is the version that developers should be targeting if they want their software to just-work™.
Sticking with the LTS sounds like a sensible idea in your case. I would suggest testing a LiveCD before you next upgrade (and perhaps wait for the next LTS - 14.04).