I worked for a company 10 years ago where we had a 401k that we contributed to. I have since left the company, how do I get my 401k money?

When you file for SS benefits they will inform you of any retirement benefits you have

If you want to access the fund sooner, contact the former employer.

Get in touch with the 401(k) plan administrator to find out how to either take a distribution or roll the asssets to an IRA. Contact info should be on the quarterly statements you receive. Or you can call the HR department at your former employer to ask how to get in touch with the plan administrator.

Be aware that if you are under age 59-1/2 if you take a withdrawal you will most likely owe a 10% early withdrawal penalty on the amount of the withdrawal, as well as regular income tax on it (federal as well as state/local, depending on where you live).