How do you get your bookmarks back after reformatting your computer ?

Any acct I may have used is linked to Gmail and I'm pretty sure which one I used, but I've never received a reply from the 'Forgotten password' ...
I'm sure I've gone thru this before and recovered my info ...
Opera doesn't seem to be cooperating this time and I want to know why ...

Well, really I want my bookmarks back

Where they went and why, would be a bonus ...

I just reformatted my computer and Opera won't sync up again, with all my bookmarks, etc ...
My account was linked to my Gmail Acct and it wouldn't let me reset my password, so I signed in with Google+ ... which has any email account I may have used to log into Opera attached to it.
Now I'm signed in, but the account is nothing I ever remember creating ... And none of my known bookmarks info are available ... That were there yesterday ...
How do I get all the info back ?
Opera wouldn't reset my password thru my gmail acct, so I used Google+ to log in.
I really don't remember passwords, acct info or which acct, but it was all linked thru Google, so it's one of 3 acct choices,
and as it would seem, Opera isn't letting me have the one I knew about ...

If I had more then one Opera Acct, it's possible - I really don't remember,
it would have been linked to my Gmail Acct.
So how do I locate any info Opera may have,
with respect to any email acct I may have used, at any point in time ?
I want my 1500+ bookmarks back ...