Another mountain bike question different bike?

Ok I was riding my other mountain bike and tried to up shift it on the front gears and it is nothing. I looked at it and saw the derailleur was about a 1-4 inch below the 3rd gear so my chain is hovering on the first and the derailleur would just grind on the gear if I tried to go into 3rd. Normally this would not be a problem but the rear shifter is having a similar problem by not going into one so I don't know how to avoid crossing my chain for this adjustment. Am I better off taking this to a bike shop or figuring out how to take it apart and fix it myself. My main problem is the rear derailleur.