Oops! It sounds like you have been a bit heavy handed with the starter on your mower and pulled the return spring out. The only way you can fix this is to rewind the spring and very carefully put it all back together. You might be lucky... There is usually a T shaped piece on the end of the spring and that will often break off and cause the problem that you seem to have. The only way to fix that is to purchase a new spring assembly for your model of mower.
Mower Man
May 2007