After your 90days already. Be fore it ends u can extend under ammesty due to covid. Have to go to your embassy to get a letter & then visit immigration again to seek approval
but Particular Services for extension of temporary stay, Notification of address every 90 days, Re-entry Permit, Visa Issuing and Changing type of Visa , could be provided only for foreigners carrying out duties relating to the specific law : Immigration Act , Petroleum Act / Board of Investment Act / Industrial Estate Authority of Thailand Act.
Contact at One-Stop Service Center for Visas and Work Permits At Chamchuri Square Building
Tel. 0-2209 1100
Office hour: Mon-Fri 8:30 - 12.00 and 13.00 - 16:30 Closed on OFFICIAL HOLIDAYS