how to update a particular row automatically after a certain time in sql

You can do that with the help of SQL Server scheduler job.
Keep a columns in that table which keeps track of the last updated time.
Write the query with neccessary condition to filter that row and update.
Then schedule this by creating a job and to do that follow these links-
how to schedule a job for sql query to run daily?[^]
Schedule a Job[^]

Hope, it helps :)