Is there a time limit for filing an age discrimanation lawsut against an employer?

Was verbally forced to retire last year,before retirement date. Was told I did not fit his program after 37yrs. of faithfull service. The owner hired 2 youger people to take my place. This was done by a 3rd generation owener of the company. There's alot more to the story,but time does not allow me to continue. Thanks!