1998 S90 first gear won't kick in occasionally

[Xochitl]

my husband is an avid s90 lover. i bought him this car as a surprise when he comes home. it almost has 200k. i bought it at a used mom n pop dealer. the problem began when i suddenly slammed on the brakes to avoid passing a stop sign ( i was doing about 30-35). when i tried to accelerate, the gear wouldn't kick in. i pulled to the side. the only way i could get it to go was to turn it off and restart it. but if i would start braking or slow down, the gear wouldn't kick in. i had to pull over many times to restart it and the darn gear knob broke off in half. Already got that temp fixed (it was previously broken), and the over drive no longer works. my question is: is it low on tran fluid? is the tran ruined? do i need to do a drain and fill? or can i just change the trans filter? i can't reach the dipstick and i can't climb into it while the car is running cause i don't wanna get hooked. oh and the orange shift up arrow and the w, s, e would be constantly flashing but that seems to have stopped when a mechanic added one quart of trans fluid. i wanted to drive up and surprise my husband for valentine day but i don't want to be stranded. it's only a 2.5 hr drive. so, how bad is it? i'm trying to save up to take it to a volvo shop...thank you for any advice!!

[DEWFPO]

Have the codes read (for free at most auto parts places) and let us know what they are.

DEWFPO

[Davwatermk]

Anyone selling a shift knob for a 1998 Volvo S90?