2002 Ford Focus Transmission Problems

:crying: My 2002 Ford Focus will not change into drive. My son slid off of the road into a corn field about 2 months ago and since then you have to put it into neutral for reverse and drive for neutral etc...but now; when I take off it goes from 1st to 2nd but will not change into drive. The mechanic I have working on it has replaced the transmission solenoids but now he said he thinks it is the computor which could cost as much as $1.000.00. Does anybody have any ideas?