Car will go forward but will not go in reverse. Does this mean I have to replace the transmission?
You should go to a good transmission shop and have them check it out. I assume that you have enough fluid in the transmission now. How long ago was the fluid and filter changed?
If you are lucky, you need only an adjustment and fluid change.
Incidentally, a “good transmission shop” is almost always an independent shop that has been in business for more than 3 or 4 years and has been recommended to you by friends, relatives, or co-workers.
It is usually NOT an AAMCO, or Lee Myles, or Cottman shop. The old joke, that AAMCO stands for “all automatics must come out”, is not that far fetched and the chain transmission shops are notorious for unnecessary repairs and repairs that are…let’s just say…not of the highest quality.