help I am a newbie.I am wondering if I should get a new fridge, will appreciate any help to fix this.

My fridge was functioning will a couple of days ago.
last night I noticed that the freezer function will but the refrigerator was very warm.some food stuff were going bad.I cleared up everything from the fridge.There was a lot of frost at the bottom of the freezer.Took a while for it to defrost.the holes leading to the refrigerator from the freezer was also blocked with ice.I cleaned these also.Open up the back panel of the freezer, saw bunch of cable, didn't know where to start.Looking at the circuit diagram , I then saw the thermostat but don't know if it is still good.After cleaning everything, out it back together and turn the fridge on, still warm i the refrigerator and cool in the freezer.Notice some water leakage at the bottom, I guess the freezer is not draining well.where do i start to fix this problem.Do I need a new fridge??
Any input appreciated.

wbawa