That all depends on your mechanical abilities. Sounds like the pedal / linkage has somehow dis-engaged, and needs to be hooked back up. OR the linkage has broken and needs to be replaced. On my 2165 HDS I can put my foot under the forward pedal and pull it upwards and get the reverse to work as the pedals are linked together. If you push down on the reverse pedal, the forward pedal raises up, and vice/versa: if you push down on the reverse pedal, the forward pedal raises up.
Try pulling up on your forward pedal to see if reverse works at all, if so check the linkages and brackets that come from the reverse pedal itself. Just a matter of following the pedal under the tractor and seeing if anything is hanging loose.
Best of luck.