I married last year. I am trying to file married/joint return, but my father already claimed me as a dependent and I cannot efile. What can I do to file married/joint?

You will have to print, sign, date and mail the tax return to the IRS, it cannot be e-filed since your SS number has already been associated with a tax return received by the IRS.

Within a year the IRS will make an investigation concerning these tax returns.  They will send both you and your father notices in the mail to determine whether or not you could be claimed as a dependent.  The loser of the investigation has to pay back any refund associated with the dependency plus penalties and interest.

there is no such thing as claiming a dependent for part of the year. if you were wed on 12/31/2022, it is you who can decide whether to file jointly or married filing separately. your father has no say in the matter. joint usually produces the lowest tax liability. regardless since he filed and already claimed you the joint return must be mailed. if your joint return showed a tax liability, line 24 of the 1040, you father can not claim you. if there is no tax liability even though you are filing jointly he can claim you provided the other conditions for him claiming you as a dependent are met. if he can't properly claim you, it's your choice as to whether to inform him or not that he should amend. if he doesn't then he will eventually get a tax bill + higher penalties and interest  because of the difference in time between when he filed and the IRS sorts out the issue. 

he could be facing a sizable tax bill. if you are the only person he's using as a dependent and he's using the head of household as his filing status the IRS would change it to single. any tax credits that he claimed by you being his dependent would be lost.