ouch, that was a pro job when mine went bad. but, lemme see if i have
this right, where i live we have the water company supply line that
comes down the street, then a branch off that leads to a pit in the
yard and there's a shutoff valve there that the water company can get
to with a 6 foot long tool. everything closer to the house than that
valve is my responsibility, so there's a line from that valve, that
comes into the basement, then there's a shutoff valve in my basement,
which is a horseshoe-shaped valve (it has a proper name which escapes
me) and that's the valve that's metered. if your on city water and
that's the valve you're talking about, then i think it's time to call a
plumber. if so, you could have them put in another valve (on the house
side of the one that's broken) too so when you want to shut off the
whole house you don't have to mess with the metered valve.

if the valve you're talking about is the one that would correspond to
my valve in the pit in the yard, here that's the water company's
problem and they'll fix it.

if you're not messing with a meter you can do whatever, but is there a
place farther up the line where you can turn the water off yourself ?

whether you do it or a plumber, if the supply pipe is old beware of
cracking it. in my old place whatever raving lunatic plumbed the house
had done so in such a way as to place the weight of the valve and
section of pipe above it on the supply line coming into the basement
fom the pit. after decades of that i think it weakened the pipe so
when the pkumbed went to replace the metered valve he had to cut the
threaded part off and rethread the pipe before beginning.