had my trans axle oil changes, how do i get my four wheel drive back ?

Look to see if the encoder motor on the t/case was disconnected. Take it back to those who serviced it, and have them fix it.

is there a switch or something that needs to be reset or something, I thought it was a safty thing thats like the e check light that comes on ?

There is no reset, especially if they just did a fluid and filter service.