Monitor won't work without HDMI switcher

Hey, so I just borrowed a friend's 4x2 HDMI switcher to connect a PC and PS4 to my Asus LCD Monitor. Previously, I had to manually change HDMI cables from the back of the monitor to switch from PC to PS4. I hooked up the HDMI switcher and got it working (somewhat) and then tried to directly connect my monitor and PC again (like it was before). The monitor is not getting any HDMI output signal anymore... I'm quite confused. I've tried different HDMI cables, and the PS4 works fine when I connect directly to the monitor.

Someone please help!

My PC specs:
-Intel i5-3470
-Gigabyte B75M-D3H motherboard
-8 GBs RAM
-1 TB WD HDD
-Windows 7 64-bit
-Nvidia GTX 460 SE video card
-Asus 24" monitor