The link account or the User Access Controls needs to be re-configured to enable all the functions again. Please follow the steps below to solve the issue. Depending on the data (current or last year's data) and license limitations, one or both of these options will be available:
Check the link to the account system: (if this option is available)
Open Housekeeping, Setup, General Setup.
Open the tab on Account No, and look for Sub-Dir for customer, vendor & chart of accounts.
Search for the correct accounting database to link with Billing. The button is a small magnifying tool.
OK to save.
Check on user access control in: (if this option is available)
Open Housekeeping, Setup, User Defined, User Defined Menu.
Select By User ID and select the User ID that you have used to log in.
Mark all first.
Exit to save.
Note: Once all the access controls are enabled, please log in again and re-configure access controls if there is a need to limit user access controls.