Thank you for your question. It was not answered immediately because it was in a different category and posted late at night. The Experts on this Site are often not available during late night early morning hours since, like others, we tend to sleep during that period and since we are all self-employed, make our own schedules. But, just to let you know, there is absolutely no online source where a person can get their employment history. There is a mechanism to order it from the Social Security Administration if you are looking for dates, etc., or a general transcript of your taxes through the IRS, but neither of them are immediate. Although it won't help you at this point, it is always best to keep your own records.
In any event, if you have more time, you can order your employment history (assuming it was W-2 employment) through the SSA by going to the following link: https://www.ssa.gov/forms/ssa-7050.pdf
Please let me know if you need any clarification. If none is needed, then if you could take a moment to leave a positive rating in the box above, I will receive credit for assisting you today. Thank you