Is there a possibility to regain vision if you had a retinal detachment?

Depends: There is good surgery for detachment if the detachment occurred and is detected quickly within 1-4 days or so, it can usually be reversed. If the macula (area of sharp central vision) is detached then good vision i s less likely if the detachment has been there for more than a week or so, then the chance of best result is lessened, .

It is possible: If the retinal detachment has separated the central part of the retina, which is called a macula-off detachment, the prognosis is worse than when it does not. In most cases, if the appropriate surgical care is given in a timely fashion, vison can be regained. It may not return, however, to the level you had before the detachment. Your individual circumstances will determine the outcome.

Yes: A large study completed in the 90's showed that 70% of retinal detachment patients regain 20/20 vision even if the retina is detached for up to 7 days.