ILG Tower Controller reported losing radios due to maintenance actions.

Narrative

I took the local position at around noon (XA:00z). at around XA:30 traffic was starting to build. I had VFR jets and props in the pattern with more on the way as well as 5 or 6 inbound IFR strips and some VFR and IFR aircraft taxiing out. Aircraft X called me 15 miles out telling me that they might need to request priority handling due to illness. I told them to continue inbound and report 8 miles out. Then my radio; 126.0; completely shut off. someone had decided that it would be a good idea to do radio maintenance in the middle of the day when we see all of our traffic. They were unable to restore the radios for approximately 15 minutes. During that time; none of my backups worked. The pet; and the brick were not able to restore communication. I was trying both the entire time without success. Our very dim light gun was also useless.After about 10 minutes without communication; the pilots started using 126.0 as a CTAF frequency. During that time several VFR aircraft landed and 2 or three took it upon themselves to depart. Most of the inbound traffic left the airspace by themselves. As I tried using the ETVS voice bypass line with my headset; I was able to reestablish communication on the radios through that line; possibly because the radios themselves were back up. I'm not sure.By this time; things were starting to break down as Aircraft X; the possible priority handling; Was on short final with Aircraft Y; a galaxy right behind them with nowhere near enough space. I sent Aircraft Y around and back to ZZZ for resequencing; and started sorting out all the traffic. After that; things got mostly back to normal and i was able to use the main radios correctly. 1. Do not allow major maintenance of critical systems; especially radios and radar to occur during periods of projected heavy traffic. This can be done either early in the morning or at night. We're closed all night. pay the overtime and do it then. 2. Make sure the backups are tested and ready to go before work is done. 3. We need a light gun which actually works. No one can see ours.