If your spped sensor does not work, the speedmeter will not work.
In case your car is a US specification car, you can make a socalled stomp test to get fault codes. The procedure is described on my website below.
Please lte us know what fault codes you get. Also look on my website for the link to European transmissions where typical faults are listed.
Have you properly refilled the trans oil amount? That is very important, also the temperature and the procedure. Also this is shown in detail under european transmission on my website.