If the DSL light is still blinking, there could be a problem with the phone cord or wall jack. Try using a different cord and/or a different jack. (Note: It might seem obvious but things happen so it's good to check... If a technician has recently been at your home, make sure you're plugging the modem into the jack the tech recommended.)
If you have tried these steps and the DSL light won't stay solid green, contact CenturyLink tech support for help.