research process - Dealing with professor after not getting back to him on a project?

I was supposed to do a project for one of my classes and I talked to one of the math professors at my school for ideas and he was excited about my project and even got one of his grad students involved.

The thing is, I didn't do well in the class and I didn't get around to finishing the project to it's fullest potential and so I never got back to him (the math prof) about it because I was too embarrassed.

I'm really paranoid now even when I'm just in the building he works in and it sucks because I'm a mathematics student so I'm there a lot. I don't want to run into him or his grad student because I don't want them asking me about the project. The semester's over now and I don't even know if he'd remember me.

I just feel like I've let him down and I really do want to work on the project I just didn't understand what equations and stuff to use after so it was just a mess by the end. Anyway, I'm just wondering what I should do about this? Should I email him? Should I just avoid him? I may want to work with him for research but I don't want him to remember this cliff hanger relationship.

Thanks!