I have an audi a4 1996 2.6 v6 the auto transmission will not select gears after i drove it in very heavy rain conditions. is there a possibility water could have gotten into the transmission and if i wanted to fill it with trans fluid i cant seem to find a fill point

You will have to dry out the harness plugs that are on the gearbox.

run the fault codes and check for problem TCM unit.

The problem is in the transmission . Run the fault codes to check for faulty TCM or servo's and solenoids. Have a pressure test done on the transmission to check for internal leaks. Remove the pan and check filter condition and while the pan is off have the bands and clutch pack adjustment checked

The problem you have comes from wiper blades causing friction in light rain conditions and can be cured by cleaning the rubber that contacts your windscreen with a rubber cleaner/conditioner or you can use spray silicone on the blades.

The basic explanation of these gears are as follows.
2up/2wd is a basic two wheel drive setting where the vehicle will react as a rear wheel drive. In this gear the transmission will only distribute power to the two rear wheels(best for all around driving with clear road conditions and will give the best fuel efficiency).
4up/4wd is a high speed four wheel drive setting. in this gear the transmission will always distribute power to all four wheels and will allow you to drive at higher rates of speed( good for poor road conditions when ice and wet roads are a moderate risk).
4dwn/4lo is a low gear four wheel drive setting where again the transmission will distribute power to all four wheels but will limit you to a low rate of speed(good for really rough roads and severe weather or very poor traction conditions).
auto gear selection is basically a all wheel drive setting, where the transmission will use a primary setting of rear wheel drive gearing until the vehicle slips or looses traction on one of the drive traction. as soon as the transmission detects a difference in wheel speed between the two rear wheels, at which time the transmission locks up the front differential turning itself into a four wheel drive, until the wheels have regained traction and remain spinning at the same speed for a set amount of time, at which time it will then unlock the front differential at return to a rear wheel drive setting. this is a good all around gear but will cause you to get slightly less mpg/kpg then a 2up/2wd gear would. i hope this helps

Sounds like low automatic transmission fluid. Have you checked the fluid level. Have you noticed it leaving spots where it's parked?
We used to have an Audi A4 wagon and the transmission was always reliable for us. We always kept it well serviced. Audi's (like all high performance cars) need very regular service and attention to be kept going well.

same reason you should NEVER steam clean under the hood,its all electronic and it hates water ingress.

Doubt it as the fault suggests you need to look into the range sensor. If similar to Renault there is a switch on the gearbox that senses where the select lever is (at the gearbox end). If the display is wrong then the sensor needs looking at and either it will need to be adjusted into a set position by moving it, or perhaps the connector to it or wiring to/from it have a fault.

auto box not receiving rpm signal, or the gear selector is not sending signal signal still thinks its in neutral. can be one of these.

check your inhibitors switch or the shifting cable.