importing or sampling

[hydromaestro]

First of all I'd like to start off by saying my PC is "PC Of s***". Consequently once my track gets deep enough it starts to chop up and skip so I have to mute certain instruments while I'm creating loops and export as a MP3 every once in a while to hear how it all sounds together. Anyways I was working on one of my tracks last night and I added one of the best guitar riffs I've ever done, then I exported as MP3 so I could hear it all together and my computer froze while it was playing and I didn't even get a chance to save my project so the loop was lost! My question is I know you can sample instruments off of tracks but I'm wondering how could I use the MP3 file (that I exported before my PC froze) to somehow import the last segment of the song and be able to continue where I left off? I really would like to do this because the segment could take days to replicate it perfectly and its a masterpiece so I'd hate to lose it. PLEEEEEASE HELP

[Viracocha]

Just import the mp3 back into the project via your software's file menu.
But you won't be able to extract the guitar, and, well, it'll be an mp3..

I know it sounds trite, but with pc components being so cheap, there's no point in putting yourself through that kind of hell - get some more ram or upgrade your cpu.
I have no idea how you could tolerate working like that

[Arpatle]

The original recording is still present probably. Check out your project folder or find out where your sequencer puts recordings initially.