Retirement tax questions

No, not my pension plan - didn't have one - MY IRA which has been converted to a 401K after I took early retirement.  I cannot go back to my "provider" - even before I I flipped everything into a to an IRA at a financial services firm I had changed employers (who used different sources for their401Ks) and they do not have records.

 

I am asking if there is an acceptable calculation to determine IRA contributions (which I have always maxed) based of years of employ in different states.