I have Music Creator 6 Touch on my Steam account. Recently all the audio files, no matter their lenght and format, that I had imported to the DAW, stay with a bad quality, like a telephone call with bad reception. Lots of interference, bumps and things like that. 
I'd like to know if there's a solution for that, because I really depend on this DAW for work and college! Thank you!

Welcome to the forum!
You say "recently", did it work OK before? What has changed?
Please give us a description of your gear and some more info on the issue so we can start guessing. OS, 32 / 64 bits?, audio interface, driver mode, what kind of audio files are we talking about (sample rate? Something special in their origin? Metadata?).  Can you record audio with proper quality, or is the problem only in importing?

Hello, thank you! =)
**Disclaimer: I'm sorry, but English isn't my native language!

So, I said "recently" because not a month ago it was just perfect! The audios were perfect and I could import/export them with high quality! About 2 weeks ago I imported a 1 hour lenght audio in mp3 format that was recorded with a cell phone and it was a pretty good and clean file. However, on the daw the sound was really bad, like "cut" in lots of places (no matter the size and lenght of the audio).
I use a Windows 10, 64 bits, I have no audio interface, only the daw itself. I was using Music Creator 6 Touch only to edit the audio files, just once I recorded a guitar using just the PC, not an interface, at the time it was everything perfect. Will do it again today just for test!  

check to see what driver is being used.
 
It's possible that W-10 did an update and reset or changed some of your settings.  I've heard people complaining about the stealth updates changing things on other forums regarding music, so look into that.

Most OS's store their house keeping records so you can "roll back" any changes. You might wish to consider "restoring" the computer to a previous date when it was working properly and then change the default to "Update only with approval"....