How did you file it? Amended returns (1040X) can only be printed and mailed - not e-filed. Amended returns can take up to 4 months to process.
It is suggested that it be mailed certified with return receipt (or other tracking service) to verify that the IRS receives it.
See this TurboTax FAQ for detailed amend instructions:
You can check the status of the amended return here, but allow 3 weeks after mailing.
Amended returns take up to 16 weeks to process, normally. In some cases, they can take longer. You can use the IRS "Where's My Amended Return" tool to track its status. IRS will also pay you interest on the refund when they finally process it!