Hi mate it looks like one of the 2 bolts that connects the leg end to the bumper, have you actually removed the bumper or is it still attached to the chassis and is your Micra a 2nd FL?
My front bumper has been on and off some many times now I can do it blindfolded lol!
Is it one of these bolts? The 2 bolts sticking out of the leg end are the main bolts that connect the bumper to the chassis!
The best way now to rectify the problem is to remove the bumper and sort out the stubborn not and bolt. I had this problem but I removed the whole bumper before removing these bolts. You will notice on the pic the 2 bolts sticking out of the box section leg end these are the main bolts that hold the bumper to the chassis.
First I jacked up the front end and removed the wheels to give better access to the wheel arch liners, I then remove all the fixings (screws/bolts) attaching the underneath of the bumper to the underneath of the front cross member then I removed the screws that fix the plastic wheel arch liners to the bumper and pulled back the liner so it hooked over the disc assembly which gave better access to the back of the bumper.
There is one self tapper that attaches the end of the bumper to the wing edge remove this, then up the inside of the bumper there is another self tapper that needs to be removed, if you have a 2nd FL on the drivers side you will have to remove the screen wash bottle which is a big pain to gain access to the upper inside self tapper and the 2 leg end bolts, then go to the front of the bumper and on each side there is a bolt by the inside edge of each headlight that needs removing. Then go back into the wheel arch and remove the 2 leg end bolts on the drivers and passenger sides the bumper should then wriggle off with not much effort!
Then you can remove and fix the seized bolt, I re-glued the bolt sleeve back to the plastic with gorilla glue it worked a treat!
I hope the above makes sense lol!

If you need any more info please ask or take a gander at my blog "Rouge 5"!
Cheers
Andy
