freezer frosting over and light no longer works

We've had this model for 2 years. We've loved it and never had any problems. Yesterday I opened the freezer (bottom drawer) and the left half of the freezer was severely frosted over... and the light would not come on??? I took everything out of the freezer and brushed the "snow" off the contents. Then I scooped out all the "snow" I could from the freezer and wiped down what all I could reach with a warm rag to thaw/remove the "snow" and ice attached to the pull out tray and the tracks in the freezer. I checked the light switch to make sure it wasn't frozen in place either, and the switch works fine. After wiping the freezer down, I closed the drawer to let it go back to it's normal temperature before putting the food back in. 10 minutes later when I opened the drawer, the light came back on and all SEEMED back to normal! So I returned the food to the drawer and closed it for the night. The next morning when I opened the drawer, the light is now not working again... and hasn't worked since. The unit is maintaining temperature and not frosting, which is good. But why isn't the light working now? I doubt it's a bulb replacement issue as the timing was highly coincidental... AND it did work for a bit after cleaning out the freezer. Unfortunately, there is no manual for this unit online, so I can't see what to do to change the bulb or try to clean out any remaining ice by removing the tray, etc. Any suggestions at to why the light is no longer working? Any links you can send to help clean the unit or replace the bulb would help as well. Thank you.