We need a lot more information in order to help. Tell us about the stairs, straight, turns with landings, how much room at the ends. Tell us about the bike. Type, suspension, make and model. Go post some replays to 10 other members (nice useful stuff vs just garbage postings) then come back here and post pictures of the bike and the stairwell. Tell us about you - state of fitness, height, weight, how new to cycling...
At 68, I work part time at an LBS so I lift and carry all sorts of bikes, even up and down stairs. I have to be pretty careful some times. Some bikes are a breeze, and not just tiny carbon bikes. Some are just awful - "give me hazardous duty pay for that one." Lots of variations. Some bikes I can bounce around on one wheel, others need a fork lift. Some are well balanced others are hopelessly clumsy. There are some tips/tricks but sometimes you need to put safety first and then just tough it out to build the strength.
Tell us much more. You may be fine or you may be advised to get another bike. I see LOTS of people these days who have dug "an old bike" out of a shed cuz they now want to try cycling. Many of those old shed bikes are the worst. Many are not worth 1/2 hour's labor cost.
BTW all my own bikes are on the ground floor so the only lifting is onto my car rack. Easy peasy.