Gear box damage.

Here's a question I hoped I would never have to ask. Ive got an old L reg discovery 1 and earlier today while doing approx 30 miles an hour someone thought it would be a good idea to pull the hand brake! Obviously everything locked up and when I had finished swearing I discovered that I could no longer get 4th gear. Reverse, 1st, 3rd and 5th are all fine, 2nd will select but not as it used to and 4th just doesnt want to know. The question is, is this likely to be pretty terminal for the box or could it be something fixable ?
Any advice would be appreciated.

what the fu-k made you do that it works on the rear prop with a diff at both ends ,as susch there is no 4th gear its the connection of input to mainshaft ,i would remove consol and gaiter then tin cover of gear box top no doubt somethings jamming gear lever

The other problem is that when in 2nd gear the reversing light now comes on!!