here is a detailed article on things to do you should read the entire article
https://www.healthline.com/health/mental-health/dissociation-coping#So-how-do-we-begin-to-pivot-away-from-dissociation-and-work-on-developing-more-effective-coping-skills?-
here is a short list of things i got from it but please read the actual article fully and consider seeking help from a actual mental health doctor
try to do some of these things also talking therapies help
Keep a journal.
Try visualisation.
Try grounding techniques.
Think about practical strategies.
Make a personal crisis plan.
Talk to people with similar experiences.
Look after your wellbeing.
Dealing with stigma.
if you are mistaking it for derealization try doing
Touch something warm or cold. Focus on the warmth or cold.
Pinch yourself so that you feel how real you are.
Try to find a single object and start identifying what it is and what you know about it.
Count something in the room. Identify what they are.
Utilize your senses in any way possible.
it looks like a lot from what i have written but it really isn't go at your own pace and please understand that dissociation and it symptoms aren't something to hide and be ashamed of and try going easy on yourself take one step at time