7U d4 oil clutch problem

There will be a drain plug right directly under the clutch in the bottom of the housing.It,s hard to say if the water caused your problem or not.Also there is a screen under a plate down under there so you should remove it & clean it.It would be best to check the clutch oil pump too after you drain the oil.

You didn't say if the clutch lever was still snapping in and out or has lost all the "snap". If it isn't snapping over center as you pull it back to engage the clutch, you will need to adjust the clutch. If that doesn't help you, before you refill the housing you may be able to see something wrong as you work the lever back and forth.

How much water and an estimate of how long it has been that way.

Oil was milky, not sure how long it's been there, clutch still kicks over center and locks.Was working well, then machine wont move.

Have you checked none of the linkage has come adrift, if ok take off the cover,start the engine, put the machine in gear,start to engage the clutch and watch the output shaft that goes from the clutch and into the gearbox,if that is spinning the problem will be beteeen that shaft and the steering clutches,if its not spinning it would mean that the power train is ok from there back and the drive loss is in the clutch area,my main suspect would be the connecting drive shaft between the clutch and gearbox,use a strong light and look down through the clutch while it is engaged and see if the centre shaft is rotating,if it is and the connecting shaft to the gearbox is static it more than likely its stripped the teeth,if the shaft is spinning going into the gearbox the problem could be several things, a gear lost its teeth,the bevel or pinion has a problem,if you can move the machine a foot and then see if you can get any drive,if you can you could be certain some teeth have gone awol.
Hope it is something simple like the linkage
good luck
AJ