was a better Quality AAC 128 kps or 256 kps

" was wondering if 251 kps is Better (it says higher quality) "

Yes.

"and another question is if all my songs are allready aac 128 if i convert will i get the audio qaulity back?"

No.

*if all my songs are allready aac 128 if i convert will i get the audio qaulity back*

No you won't, information was already lost when the original file was ripped to 128 kbps. To get a higher quality file you need to re-rip from the original uncompressed format rather than converting from one lossy format to another. In fact converting from one lossy format to another can result in even more quality loss. It's a bit like photocopying a photocopy, the farther you get away from the original the lower the quality. Ripping at a higher bit rate will give you a slightly larger but higher quality file.

If you want to do a bit more research have a look at this article, you'll get an extensive comparison of the AAC and MP3 formats and bit rates benchmarked against CD format: Planet of Sound - Quality of AAC audio and MP3

You're welcome, I'm glad the information was of some help. Take care