I have slight crowding on my top teeth. i had braces , my retainer does not fit anymore. any methods i can take without braces or invisalign?

Not really: Correcting the misalignment after orthodontic relapse requires active tooth movement. And commitment to wearing the retainer, perhaps indefinitely. You can likely use a removable approach such as invisalign, or bioliners. Removable rigid appliances with springs on the inside can be used. Cosmetic dentistry like veneers is probably too invasive.

Orthodontist: Your orthodontist can fabricate a removable appliance that will gently move those teeth back into place. It looks like a retainer, but will have sprigs and wires that apply pressure to move the teeth.

Yes: See your orthodontist. Our practice for example also sometimes employs custom aligners that we create to resolve these issues.

Maybe: Return to your orthodontist to explore options for improving your mild changes. Sometimes, a different type of retainer can be used to return them to a more ideal position. Then, make sure you use your retainer.

Yes: You could try having enameloplasty, the teeth can be slightly reshaped and recontour also coupled with bonding. However progressive crowding is a symptom of an unstable bite and generally needs correcting. Especially with someone in their 20's it will only continue to get worse. Their are active retainers that can correct the problem also.

Not really: That ship has sailed. 2 choices: 1) do nothing and watch relapse intensify, or 2) restraighten teeth and then diligently retain the correction. Know that if you have teeth capped to make them look straighter, and they continue to shift, you will have wasted the cost of the caps.