Can any body help me because my bonnet can't open please help

What actually doesn't work? Is the key not turning on the lock?

Take a look on YouTube there's some videos on this

Plenty of answers on the Focus Forum, just do a search. 

Yep, I just had the same problem and followed a combination of several threads on this forum and Youtube videos, the best solution just depends on exactly what is wrong so there is not one solution to fit all.  The search function on here works well enough to find topics using key works "bonnet lock" or "bonnet not working" etc

I recently fitted custom grills to my MK2 facelift 58 plate Focus. When doing the top grill (the one with the ford badge on it) I 'broke' my bonnet lock. IE, turning the key wouldn't activate the locking release on the catch when turning left of right.  This was because the locking mechanism has an anti theft design. (very poorly designed btw). Now, this will only work if your problem was the same as mine. (assuming you have a MKII?)

I recently employed this solution and it worked, with plenty of elbow grease.  If this works, the once open, you can apply the same technique until the locking mechanism is fully working again.