95 mitsubishi galant

this is a manual tranny?

oh I see its automatic, is there a check engine light on? and does it just shut off by itself after you start it?

Other than checking the fluid level, have a trans shop check it out.

But when the trans fluid and filter was changed, they may have put wrong filter on or got some debris in valve body.

There isn't any check engine lights on and it doesn't turn off. I had someone look at it from a shop and they said that somthing inside was broken but thats all he said. I thought he wasn't being honest with me becuase he wouldn't give me an explanations to my questions. Also the car will roll when place in nutral.

Will it roll in park? Have you checked the linkage to make sure it is still attached?

As far as the issue, if the trans fluid is still full and clean and doesn't smell burned, it sounds like an electrical issue. My first guess, if nothing works, is the trans control module (TCM). If it doesn't shift from 2nd gear (stays there all the time), then it is in limp mode. That is to get you home or to a shop. You need to have the TCM scanned to see if any codes are stored.

Just fyi, it is normal for the car to roll in neutral.