http://support.microsoft.com/default...;EN-US;Q242165

That support item shows the procedure for REMOVING the accounts option in the tools menu.

Work it in reverse by changing the "no accounts option" to "0" (zero) if present from the registry that the article linked above says to change:

To remove the Accounts option from the Tools menu:
1. Start Registry Editor (click Start, click Run, type regedit, and then click OK).
2. Locate the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Outlook Express
3. On the right-hand side of page, double-click the No modify accts value.NOTE: If this value does not exist, on the Edit menu, click DWORD Value. Type No modify accts, and then press ENTER to save the name.

4. Change the setting of this value from 0 to 1, and then click OK.

If that doesn't work post back here.