2005 Ford Explorer Trans Problems

[Stacypub]

Ok so Kentucky just had a major snow my husband decides to drive my 05 Explorer to work because it is 4 wheel drive. While in the lot the Explorer is all but buried by snow plowing nearby. It takes me about two or three days to one get to it and then get someone to pull it from the snow bank in front of it. Once out in the clear the Explorer will take gear but will not move in any gear except 1 and that is just a little. After some time working with it and thinking it might just be really frozen up I give up and tell my brother who is helping me to call our tow truck guy. When the tow guy arrives he does not have a flatbed to haul it so he suggests that I push it into an empty parking spot until someone can come get it. While he is moving his truck I make one last attempt to get it to move and it does in all gears. I managed to drive it to the tow guys house who lives down the street from me because his drive is clear of snow and mine is not. The following day I go to move it to my drive and guess what it happens again Explorer goes into gear but does not move. My Dad gets in and tells me to change it between 4 wheel low to high and then back to auto to see if that helps and it did Explorer moves and I get it home. It sits for a day or so and I start it again today and wouldn't you know it no movement until I do the 4 wheel thing again. My Dad believes I have a trans filter clogged up. Any one have any input on this? Does it just need a trans filter and fluid change or is there something else wrong? Again this is an automatic Trans 2005 4 wheel drive Explorer.