One of these will do it, but will cost you about the same as having a plumber come out.
Just got ready to remove my built in base cab for bathroom remodel and I have to take the ends off because there are just 2 holes cut in back of wood cabinet for plumbing. Went to shut off water at main and it absolutely will not budge...probably hasn't been turned in 30 years. Any ideas how I can proceed? I need to finish with cabinet demo before hubby gets home
1. Have a plumber's phone number handy.
2. Use a wrench to try to turn the valve handle.
3. If the handle breaks off or it does turn but never stops turning, see step #1.
4. If it does turn the water off, but never stops turning when you try to restore water pressure, and you do not have any water, then see step #1 also.
The speed version of HJ's advice: Refer to step #1. Save the can of worms you would be opening for a day at the lake fishing.