You can take the top off these things, to separate the electrical bit from the the plumbing bit. Then you can discover whether the plumbing bit is jammed (unlikely), or whether the electrical motor and microswitches are causing the issue.
With the electrical bit separated, you can inspect it to determine type.
Some of these two/three way valves can just have the electrical bit replaced, but it generally costs only a few pounds less than a complete unit.
So buy a complete unit and just change the motorised unit.