Torn hamstring- cant exercise. HELP!!

Ouch, sounds painful? How did you manage to tear it?

I'm no expert by any means, but I would suggest lifting weights, if you aren't already - and even if you are, make it your main focus now. Focus on the upper body since you obviously can't to squats, deadlifts, etc. It's not cardio, but it's something. And increasing muscle tone will help you burn more calories throughout the day. Just make sure you up your protein to support weight lifting.

I tore my hamstring 2 weekends ago and i have been strictly told i can not exercise for a month and the muscle upon healing will be tighter then before so i have to spend up to another month stretching it out before introducing no impact exercises. Does anyone know how long this will take to fully heal so i can start running again? I have no idea how anyone can put up with not exercising. If anyone knows any fabulous ideas to keep me sane and burn some energy i would much appreciate it!

Yeah, this is a fairly brutal injury unfortunately and it affects everything from a lower body perspective and even much of the upper body work. The only thing you can probably do it work on upper body. Focus on compound upper body movements such as Bench Press, Incline press, Dumbbell press, Shoulder Press (seated because you can't stand and do these), Chest Supported Rows (if your gym has one). I've injured my hammies both a couple times and it takes time for sure, just be patient or you'll make it worse. When you do get back, make sure you put some focus on developing your posterior chain because often (not always) these injuries are related to a muscle imbalance between the quads and hammies.

This happened to my friend, her PT told her it was ok to spin.

That's not a bad idea and your injury will tell you REAL quick if you can or can't do that. Perhaps start with just a recumbent bike first though.