It is broken. Take it to your local fix-it shop that does repairs on RC cars. Maybe you could download a manual for it with detailed instructions on how to take it apart and fix every conceivable problem that might occur with it. Perhaps your local parts distributor or RCpartsRUS had the part in stock.
Seriously, try not walking into walls. The dizziness should go away soon and you will be able to move the lever in the reverse direction again.
Leonard