Shimano Deore FD-M590 replacement
Did you try adjusting it yourself? http://www.parktool.com/blog/repair-help/front-derailleur-adjustment 

Did you rule out the shifter/cable/cable housing causing problems? Try manipulating the cable tension by hand to shift it to see if this is the case and then work from the problem if it doesn't let you move the cage with reasonable cable manipulation. 

If it doesn't adjust and the shifter is good, I'd just replace it with the same thing that is already on there (note that you need to get the right clamp and cable pull type for your frame, so you might as well order it from the bike shop if you don't know what clamp type and what not you need). 

FD's are relatively simple parts that don't have a wide range of performance between grades, and its just about as cheap for what you have as with the lower group parts.