I have a 2000 SSEI
with shifter in OD (Drive) or 3rd car wont move .
but will when shifter is put in 1st and 2nd.
if i start in 2nd it will shift automatically from 1st to second and manually shift it I can shift to 3rd at about 35 and OD at about 50 but when i stop it wont move unless i shift it back to first or 2nd.
reverse works fine also
any help would be appreciated.

Probably something mucked up in the valve body.

The valve body is in the side pan, and you have to drop the transmission to get to it.

How deep are you willing to dig into it?

Have you ever dropped the pan & installed a new fluid & filter? Use Dexron 6. How many miles on the trans?
On level ground, after driving for 20 minutes, check the transmission dipstick while in park running, to be at the full line or slightly above.
Is the fluid clean and and not smelling burnt?
As this is an electronically controlled transmission, anyone with a good shop scanner, can scan the transmission for any problem codes. Post back any codes found.

as deep as i have to just didn't know if it could be a solenoid causing it not to move in drive or 3rd

Most likely the problem!
https://tripleedgeperformance.com/no-movement-in-d-or-3