What do you mean you lost it? Did Google deactivate it? I also have my GV since 2010 and I haven’t connected a US number in a decade (I do have credit on it)
I lost access to this Google Voice number. I received an email that I need to activate it and that means I had to attach some US number with it and verify with some SMS. I could not do it. I do not have any Google voice number on my account now. Also, I might have missed that "send at least one SMS or make a call every certain number of months" at some point.
