Question Liquid Cooling stopped working. How do I turn it back on?

[Carondalet]

Pardon me for having only basic to intermediate PC knowledge. Thanks in advance for you time.
Corsair Hydro Series H75 added to computer a few months back. Was working fine. All of a sudden stopped. Can't seem to find a way to turn in on? I have a lot of dumb questions, I'm sorry, but this is one of my most important dumb questions. How did it stop working? How do I turn it back on? No drivers to download, it's just supposed to plug in and work, right? Did a Windows reset and still isn't working. All the other fans are working, but liquid cooling is off.
Thanks for any help. Much obliged.

 

[Ralston18]

No problem with questions.

And you are wise to ask because loss of cooling and the resulting high temperatures may not end well for your PC.

Update your post to include full system hardware specs and OS.

Include PSU and more cooling system information - temperatures....

Any error codes, pop-up windows? Signs of leakage, noise, smells?

Have you powered down the system, unplugged, and opened the case for internal inspection?

Could be a loose wire, something jammed or stuck.

Take and post photographs if you deem necessary:

http://www.tomshardware.com/answers/id-2173703/post-images-tomshardware-guide.html

 

[Carondalet]

Thanks for your reply!

SYSTEM SPECS:
CPU: Intel (R) Core i7-4770
RAM: 32 GB
GPU: NVIDIA GeForce GTX 950, but it will be the 2060 KO next week.
Motherboard: Lenovo – need a new one - looking into that as well.
Cooling: Corsair Liquid Cooling
PSU - EVGA 650 GQ
Windows 10 home edition, 64 bit
Version 1903 installed today

No error codes or pop-up windows regarding cooling. Only error message I've received in the last few months has to do with MiniTool YouTube Downloader not working.
There have been no smells, leaks, noises, except one of the original fans has a slight buzz.
Have done a power down and inspection, haven't seen anything missing in the way of connections to the cooling system.
The computer is currently open, as I am about to switch out the graphics card to the RTX 2060 KO when it arrives. However, there have never been any performance issues with the GTX 950. Has always provided smooth gaming at 60 fps and seemingly perfect use of Photoshop and Lightroom. Only a little lag when doing some of the more powerful tools. As mentioned, it has been getting slower throughout the Spring. Simple games like the new Ori, which is just a platformer, has really nasty lag and distortion whenever you fight any enemy.

Thanks again.