I was in the army but didn't get a W-2 from them, what should I do?

If you do not receive your W-2, IRS.gov has remedies:

Call the IRS. Taxpayers who are unable to get a copy from their employer by the end of February may call the IRS at 1-800-829-1040 for a substitute W-2. The IRS will send a letter to the employer on taxpayers’ behalf. When they call, taxpayers need their:

Name, address, Social Security number and phone number.

Employer’s name, address and phone number.

Employment dates.

Estimate of wages and federal income tax withheld. Use a final pay stub for these amounts.

@yaz125 

Well..it could have just been lost in the mail...or maybe you separated and moved to an address they don't have.

IF you are still in-service...or departed within the last 13 months, you can still get the W-2 form using the DFAS's  myPay login  (or two other options shown here):

https://www.dfas.mil/militarymembers.html