So apart from a new guitar is there anyway to sort out a rounded out allen bolt hole in the head of the guitar as my string action is at places 5mm off the fret board and its starting to annoy me in playing and enjoying playing, The previous owner must have ruined it at some point. :(

If it is a 5mm allen bolt then you can hammer a 6mm torx key into it.

Oh good idea doesn't matter if I break my guitar now it cost nothing and is worthless, And I am planning to get a new one soon anyway. :)

If it's a bolt on, you can take the neck off of the guitar, and use clamps to straighten the neck (sandwich the neck between two piece ofs wood, protecting the frets with cardboard or something) and ease the tension of the neck on the trussrod -- this will make it easier to turn. It's possible there's still enough tooth for that.

 

Otherwise, try filing notches, that way you can use a flathead screwdriver.

If you just want to adjust your guitar its a good idea. Otherwise you need to delaminate the fret board from the neck. It's not terribly hard this video is great:http://www.youtube.com/watch?v=vrLUslIeFMc

Damn software double posting

If it is a fender style you should be able to remove the strings and have a friend CAREFULLY bend the neck just enough to release tension and you can unscrew the nut all the way off with some needle nose pliers (or something similar) and get a replacement one online.

 

Have you tried American sized allen keys?  Sometimes it isn't a 4mm but a 3/16 or 7/32 even.  4mm and 5/32 are virtually identical so sometimes one strips out the other.