Judy,

Online Mass does not fulfill your obligation. You can certainly watch it of course, but it can't replace being there.

That being said, if you can't make it to Mass, you can't make it. It's not a sin not to do something that's not possible. But perhaps you can try calling the parish and see if they have someone who can give you a ride, or consider Uber or a taxi, depending on where you live.

Make sure you exhaust reasonable options.