sounds to me like you've just disturbed the shift mechanism, no big deal. unscrew the gearknob and pull the trim from the gearshift surround. under there is a plastic cover held on by 4 x allen screws, think they're m6. anyway, remove them, you'll probably need a quarter drive socket set with some allen key bits for it as it's a bit awkward.
once you have the cover off if you look down the left hand side you'll see a 8mm allen bolt that attaches the shift arm to the selector rod, chances are this has moved. i'm taking a stab here but i suspect your lever is no longer standing straight up in the neutral position. you need to slacken this bolt and move the lever gently back to where you think it should be. basically what's happened is the alignment of the lever has moved in relation to the gearbox so now you're having to move the lever further to the left to hit first but before the gearbox selects you're hitting the detent for reverse.
Clive had exactly the same thing when he took his in for MOT except he couldn't get reverse. i'd guess that it'd be unlikely you've done the synchro on both gears, in any case even with a knackered synchro it should still go into gear with the engine turned off. i wouldn't worry too much at this moment, have a look first
At first when i crunched the gears it was all over the place, would go into 1,2 but not 3, then if you put it into 5 it wouldn't go into 1. It seems to have settled on 3-6 and R ok. To answer your Q, i won't go into 1,2 even when the engines off.
I didn't really feel that gutter TBH when it happened. knew it was fixable
i think with all the ragging about you've managed to move it over slightly, don't worry about it, it's a half an hour fix, Clive will probably be along soon to tell you what happened to his. in fact whilst you're in there you want to pull the lever and do my shortshifter mod. basically you drill a hole lower down than the existing pivot point then move the bolt, once you get the lever out it'll all be clear, doesn't half make a difference to the change.
Still broken! i'm depressed. It's something more serious now, possibly 1st and second gears need a rebuild. Its going to a gearbox place later. The exhaust is banging because it's bent! so it needs replacing to stop said banging. My mechanic said at startup there was blue smoke out the rear. After startup it's only a little white and not blue!
SO i'm really fedup! £££ which ever way you look at it! I better call Doug and cancel that remap tomorrow!