Number plate bulbs not working!!!!

Just tryed to change the bulbs to led in number plate. One came on the other didn't, then whilst still switched on I took out the other one that wasn't working and swapped it round positive and negative sides, the other one then went out and now nothing works, not even the old bulbs!!!!

What have I done!? I checked the fuses under the steering wheel and all are fine, including the ones you can't get to. Is there fuses anywhere else?

I'm not impressed!!! Someone help!! Thanks
 
they are polarity scensative, led 501 bulbs have + and - and wont work put in backwards.