GermGuardianGenuine UV-C Air Purifier Replacement Bulb AC4100, AC4175 & AC4150 Air Purifiers, LB4100

The night light is burnt out after only an hour of use. How can I replace the light to get it working again?

Is this the correct replacement i’ve bulb for purezone air purifier #peairplg?

How do i know uv light is working? i can not see any uv light while the uv light switch is on.

What is the length of just the light bulb not including the wire and connector?