Refridgerator Freezer Is Not Cold?

This morning we noticed our fridge was not that cold and the freezer food was starting to thaw. The unit is a 10 year old Whirlpool Side-by-side. What are somethings to check? The wife wants to buy a new one, but I wanted to a>see if there is something I can check first then b>see what it costs to repair to have service come out. Any advice would be greatly appreciated.