Just installed a bathroom in basement . I teed off the existing water lins but I have only a trinkle of water in taps and shower. The upstairs is still fine. I used the flexible 1/2 in water pipe.

"Just installed a bathroom in basement . I teed off the existing water lins but I have only a trinkle of water in taps and shower."

What's happened here is that in taking off the water you disturbed some mineral build up on the pipe walls and now it's blocking the inlet ports in the valves.
Shut off the water, open up the faucets and clean out the crud from the cartridge inlet ports. Beforeyou button up the faucets and while their still open turn the water back on for a minute to flush out the supplies. Let me know how you make out. Regards, tom

Speedball1

Your suggestion worked great. Thank you.