The IRS can research the status of your refund if it's been more than 21 since your return was accepted. Call 1-800-829-1040. The IRS phone lines open at 7 a.m. in every time zone. Call waiting times build quickly.
Common reasons for refund delays are reporting the wrong stimulus payments on your return or using 2019 income for the Earned Income Tax Credit or Child Tax Credit.
Check out the post by @DoninGA for more instructions and options, including visiting your IRS office or contacting the Taxpayer Advocate.
What to do when it's been 21 days and I haven't received my federal refund?