A few days ago i realized a very loud gringing noise comming from my car in reverse. It didnt seem that bad at first but then a few days latter it started grinding even louder... And yesterday it started grindign in 1st gear. Whats the problem, is it the clutch? Flywheel? Do i need to rebuild my tranny? Thanks for your comments...

 

Can you shift smoothly in every other gear? If so, it's unlikely to be your clutch. Flywheel is unlikely, as it has little to do with the actual gear change. Chances are that you've got some gear/synchro trouble inside the tranny, and the only remedy for that is a rebuild.

Check your tranny oil to make sure that 1) you have some, and 2) it's not all burnt to hell. If either is the case, you'll need to add more or change it out (as well as find out where your leak is, since there's no way your tranny should consume/leak oil normally).