Why won't google let me sign in to my gmail?

I tried to open my gmail from a computer at my local library. I used the right password, but it asked me for a verification code which it sent to my alternate yahoo email (which I could open) and the answer to a security question (which I answered correctly), and it still denied my sign-on, saying they couldn’t tell if it was really me. I tried this sequence 3 times with no success. Back home I got a message from gmail saying someone had used my password trying to sign in.

Why won’t it let me sign on to my own account?

It was suspicious in the first place because it didn’t recognize the device you were logging in from (hence the extra security measures). As for why it still didn’t let you in, best guess is that you got part of it wrong (most likely the security question).

Yesterday google wouldn’t accept a 2FA it sent me. Either something is wrong, or they’ve made some design decision that affects corner cases (like you, I was trying to do something different on something different)…

I know I have a gmail account, but I can’t get to a login page. Instead, I’m taken here:

Add Gmail to your Google Account

By completing this form, you’re upgrading to Gmail, email from Google. Gmail works on any device, blocks spam, and much more.

You’ll be able to sign in using your new Gmail address, which will become the primary email address associated with this account. We’ll send account updates, invitations, and other notifications to your Gmail address.

[my primary email address] will become an alternate email address on this account, and you’ll still be able to sign in with it.

If you prefer, you can create a new Google Account with email, and leave this one as-is.

There’s a place where I can choose a new gmail address. Why can’t I use the address I already have?

Come to think of it, I did have a similar experience recently. I was looking up directions on my computer, and clicked the button to send it to my phone. In the past, one option that brought up was "Send to ". I have a new phone now, though, and the only options it gave for that were my two previous phones. It said that if I didn’t see my phone listed, I needed to connect it to my Google account, and that I could do that by accessing my gmail from it… which I had already done.

I don’t know about yours, but my library does not allow emails on their computers, so that may be why

I can get Yahoo email with no problem at the library; it’s Google itself that seems to have me blocked.