Grub Issue when installing Manjaro

I installed Manjaro, and since then no version of Grub will let me choose and operating system, except the one at the top of the Grub menu. Hitting My Up Or Down key makes no difference. If I hit “e”, nothing happens. It is as if the Program responds to no input whatsoever.
A week ago it worked fine

In other words, you do have the Grub showing, but no (keyboard) input is detected. Did i get that right?

Yes, grub shows up, but is totally unresponsive to anything on my USB Keyboard, Grub just does the countdown and proceeds to Manjaro. My Daily Operating system is Linux Mint.

Its likely a bios issue, the OS has not loaded when you see the grub menu. Especially if you have an old motherboard with a PS/2 port for the keyboard. There may be a setting in the bios to allow a usb keyboard, and there may not be depending on the age of your hardware. I would also look for a bios update that may enable the usb keyboard during boot. The only reason I know about this is my ancient hardware needs a ps/2 keyboard or you cant do anything in grub. If you reset your bios, or the battery on the motherboard is weak and your computer lost power causing the bios to reset to defaults, its likely a bios setting. If its an old battery replace it so once its set this doesnt happen again. But your likely to need a ps/2 keyboard to enter the biaos setup to look for the setting.

This issue lasted only 3 days, it worked fine after that and do not know why it went that way

This computer was brand new (Built for me) less than 20 months ago

The USB ports that are initialized at boot during GRUB is up to your MB. You need to look for something in the bios/efi that will enable the usb port you are using for the keyboard during boot.