Are you kidding me? You didn't pay into anything. You just paid an income tax that was fancifully labeled the Medicare tax.
You don't get your taxes back, with or without interest, and being a taxpayer doesn't give you a vested right to any welfare benefits.
You do not understand Medicare at all and probably should shut up until you learn something.
Wage earners paid into Social Security all their working lives and then received a relatively small pension when they retired.
If the pension is, say, $2000 a month, a certain amount is deducted from that pension for Medicare. It's like paying an insurance premium. Now, this is a bargain because Medicare is great and it's most great in case of disastrous hospital bills.
The Medicare tax has nothing to do with income tax. You don't pay it at all unless you are receiving Social Security.