Hello Michelle and welcome to JustAnswers,
As for gathering your past employment records, retrieving it by tomorrow is difficult at best. The best and qualified way to retrieve your info would be to contact social security as for a fee will be able to send you your past employment history. Problem is this takes a few weeks to collect and mail back to you.
In terms of finding your past employment history a bit quicker, some suggestions I can offer:
1. State Unemployment agencies can often release employment histories for individuals, as long as they worked for in-state employers. Check with your local office tomorrow to see if they can pull up your past employment history in their office.
2. If you have saved copies of your tax returns, you should have your copies of your W-2 forms. This will give you a good overview of dates and years you worked for past employers.
3. I would also sit down and write out every employer you remember working for. Then call tomorrow as many as you remember in order to get dates when you worked.
While there is no quick online service that can offer this information, you can try looking at pulling your recent credit report as it can offer past work history going back a number of years:
Overall, go ahead and fill out the info for the employer with your best estimate on when you worked. Employer will usually run a background check to verify employment so just being as truthful as possible will be enough to get the job.
I wish you the best of luck in getting the job. Please let me know of any additional information/concerns you have. Also if you could please take a moment to rate my help so that I can receive credit for assisting you this evening.