Ifyou are admin, go to Admin >> User Management >> Users and click on your name to see that you have access to all groups. If not, select everything, re-login and see whether you can see Data warehouse
If you still cannot, go to Admin >> User Management >> Groups, create a New User Group at the top right, select the report suites, give "All Access" to all the Report Access and pull your name into the group members to select okay. Re-login again, you can see it for sure!
If you are not Admin, you cannot do any of the above. So please reach Admin to give the access in the same way as said.