What's with my laptop Wi-Fi adapter?

It'll turn on one moment, then the next, it's non-existant and i can't connect to any Wi-Fi network. I've looked at the battery settings, but i can't find any Wi-Fi adapter disabled or anything. Why does it keep turning off. And normally, when it turns off, i'm forced to restart the laptop and hope that i can finish what i need in the few minutes before it turns off again. Any ideas?

Added (1). Okay, it's a lenovo thinkpad t400 with an intel adapter. Don't know how that helps. It's a laptop issue since it just changes. The reason i guess laptop because when it's working, and i pull up the wireless broadcasting window, i get bluetooth and Wi-Fi, but when my laptop refuses to connect to any Wi-Fi, and i pull up the wireless broadcasting window, i get bluetooth only, the Wi-Fi option is non-existent.

Lenovo Flex 2-15: Can't connect to wireless Internet after installing Windows 10. How to fix this?

So we just bought the Lenovo Flex 2 15 laptop about a month ago. It came with Windows 8.1. When we first used, we tried connecting to the wireless internet in my house (The router has no problems). No Wi-Fi connections were showing up at all. To solve the problem, we downloaded the driver and the Wi-Fi worked successfully.

So we installed Windows 10 yesterday and now I see a list of wireless connections. But when I click any of them to connect to, Windows would say, "Can't connect to this connection". I repeatedly tried this and even restarted my computer many times. I even did research on the Internet about this stuff. I also tried diagnosing the network problem on windows and I read some codes. The issue was that my computer was not authenticating with any of the connections. The only thing I did not do was call a tech support from Lenovo.

Does anyone have this problem?

Looking for a place to order screws for a laptop online?

My computer has lost screws in the bottom and I'm looking for a trustworthy place to order for my laptop. I have Lenovo Flexpad 2-15D. It's hard to find the correct sized screws online and the company charges $20 per screw.
Here's a list if it helps reach an answer any faster:
M2 6 mm, flat-head, nylokcoated
(8) (Flex 2-14/Flex 2-14D)
M2 3.5 mm, flat-head, nylokcoated
(4) (Flex 2-15/Flex 2-15D)
M2 6 mm, flat-head, nylokcoated
(4) (Flex 2-15/Flex 2-15D)
M2 2 mm, flat-head, nylokcoated
(3) (Flex 2-15/Flex 2-15D)
Thank you for all of the help!

Added (1). Unfortunately, the distributor that I bought the laptop from went out of business. The reason (albeit) why the quality wasn't that good and the screws came out, and the warranty doesn't cover screws for Lenovo. :\

Key popped off on keyboard?

My school gave us all laptops, I've had mine three years, little damage other than a few scratches and such from use. Well, today I was typing a report for english and the N key popped off, it still works and I have all the parts besides the little rubber thing that goes under the key. My school will charge me fifty(50) dollars to fix it! Thats a ridiculous amount! I was wondering if I could take it to a repair store and they could fix it? Would it cost more to have it fixed there than the school? How much would it approximately?

Added (1). lenovo thinkpad x131e chromebook 11.6" led intel celeron dual core 1.50ghz model 628323u

My computer won't turn on?

Yesterday my little sister dumped a cup of water on my (closed) laptop. She said it was only a little bit and only on the top part, but it won't turn on and whenever I plug it in, the light on the bottom right corner of the keyboard, cover, and the power button blinks three times and then that s it. (it is a Lenovo ThinkPad)

Any idea how I can fix it?

Thanks!

BTW: I took out the battery over night because there was no water underneath the computer, it was just on top of and where the screen hooks onto the keyboard in the back.

Recommend me affordable laptops that don't make noise?

I'm planning on getting a new laptop and I'm not sure if I should get Acer, Asus, Toshiba or Lenovo. Can you please recommend me laptops that don't make noise or heat up a lot? Your help will be appreciated.