Hey-yo,
I have problems with my keyboard and mouse sometimes when I turn my laptop on. They're just not working. Somewhere I read that it has to do with a so-called "blind registration" and that I only have to tip in my password. But no matter how many times I do that it doesn't work. I'll always have to turn off my laptop and turn it on again, hoping that it works.
I only have Linux for two months and that's the only problem I got until now. Please help ^-^'

please, tell us at least the type of the laptop. (I have no idea what's that blind registration).

I've used Mint on several computers and never encountered anything of this nature and have never heard of anything called "blind registration" (that's not to say it doesn't exist, but a web search for "blind registration" linux turns up nothing).

The first thing to do is to rule out hardware as the cause of the problem, as no amount of software troubleshooting in world will fix a hardware problem. Here are some tests you can run:

The next time this happens, try unplugging the devices and plugging them back in. If they don't work in the same ports, try different ports.

If you have another keyboard and mouse or can borrow them from a friend for testing purposes, try swapping them out to see whether the problem persists through enough reboots to give you grounds for a reasonable conclusion.

Boot to a Live CD of something that's not Mint or Ubuntu-based and see whether the problem occurs with it.

If that doesn't help, try providing additional information as suggested by pan64. The more information you provide, the easier it is for others to help you.

My laptop is a Toshiba Satellite L770D-10G.

Before it was that I had windows 7 and something like that never happend in 2 years. It started as I installed Linux on it.
And with that "blind registration" I looked it up in the german instruction, but in the english version it's nowhere mentioned :/