Your first priority is to find out why your work isn't being used.
Things that come to mind:
Your software may be solving the problems.
Find out what people actually need. Talk to them, alone or in groups. Alone is better initially to get unbiased feedback (but you yourself may be a source of bias).
Your software may be underexplained.
If it's complicated to use, people will want to use it but never quite find the time to get the complications under control
It may be hard to get the relevant information out of you.
If you fail to understand why somebody is having a problem with your software, or if you perceive your user as, ah, mentally challenged, or there's some similar problem:
Whatever the education problem: you can't change your user base, so you have to train talking to people who're not at your level.
Usually, they aren't dumb, they just aren't trained in the things that you take for granted. Though dumb users do exist - but if you want to talk to them, you still have to find a way to reach them.
And you have to completely switch off the "they are dumb" thinking: Your nonverbal communicaton will betray that thinking. Even if you know it's unhelpful. You can try switching it off just for the meetings, but very few people can fully suppress their true feelings, usually enough will leak that the other side will at least notice something is odd.
I know it is really to change one's beliefs about one's peers. Usually it's easier to find something that you can respect about your users: Talk to them, listen to their situation, try to understand what their motives are and what's making them tick like they do; usually, there's something of worth to find.
It may be hard to get the relevant information out of you (type 2).
You might have difficulties explaining yourself, resp. your software.
The only thing that helps here is gathering experience, accepting failure as a way to identify what to improve.
You may have been sidelined.
Not necessarily by any fault of your own.
E.g. sometimes companies hire people just because they know they need them six months later. Sometimes that six-months-later timeline gets extended.
The risk for you is if the company did so because of some management mistake, and as soon as they find out, you'll get fired, and the responsible person has a big incentive to find some reason to blame you. (You should ignore the blaming, it's about the person's standing in the company, not about you - you won't get a glowing reference, but your next employer will know that such things can and do happen, so even a bad reference isn't necessarily a dealbreaker.)
You can try to find out if that's the case - try to find somebody who's interested enough in your department to know what happens but disinterested in stakes anybody might be having.
The nasty variant of sidelining is that somebody is setting you up as a scapegoat.
Tricky situation to handle, tricky to detect in advance.
The best approach I know about that is to not assume anything but be prepared for everything. It's not a good approach because it will color your day-to-day interaction with your colleagues (and this can become a self-fulfilling prophecy). Your options in this scenario depend heavily on interpersonal communication skills.