The IRS WMR tool tells you exactly what to do and how long to wait before contacting them.
Check your paperwork, on the filing instructions page it shows you where you were having the refund sent. Is your routing & account numbers correct? Did you confirm them with your bank? If they are wrong then the IRS will convert your refund to a paper check and mail it to the address on the tax return. This conversion process can add 3 weeks or more to the time table.
