If you did not uninstall boot9strap on purpose, it should be still there. Can you access Luma settings by holding (SELECT) while booting? If so, CFW is still installed (normal "Format System Memory" does not delete B9S).
1. Check if your buttons are working.
2. Maybe you have changed Rosalina button combination. → rename SD:/luma/config.bin to reset Luma configuration.
3. Luma versions before v8.0 did not have the Rosalina menu.
→ When bringing up the Luma settings by holding (SELECT) on the top of the upper screen there is Luma3DS v??? configuration
Depending on the version number you will have to do different things: