[Help] Another no0b victim of W3 Total Cache logged out of his site

Greetings,
I would really appreciate if you please take the pain of reading this lengthy post.

I’ve a self-hosted wordpress blog: http://mrunal.org

Two days ago, I had installed W3 Total cache plug-in and everything was working nice and smooth.
But Today evening, When i tried to log into my control panel, it kept giving error

Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

I googled around, and it seemed that W3 Total Cache is the culprit. So I followed the instructions regarding “how to uninstall W3 Total Cache without dashboard“. I did that (deleting the .php files and folders, related to that plug-in.)

BUT unfortunately my entire website went down.

It’d only show some “hello World” like wordpress page. Even when I tried to login into admin panel, it refused to accept my password. and I can’t recover the password using the password recovery form, it says my email id doesn’t exist in the database!
I googled again, and it seems that to recover password from self-hosted wordpress, i’ll need to do something in MySQL.

Anyways, so now I thought of undo-ing every step I did earlier. So I restored those W3-Total Cache related files and folders (ya thankfully I had taken their backup before uninstalling W3TC)

Now my website works like before but I still can’t log into my dashboard. It says

W3 Total Cache Error: some files appear to be missing or out of place. Please re-install plugin or remove “wp-content/db.php.”

So, I removed the said “db.php” file, then it shows me a log in page but doesn’t accept my password.

What I understood from trial and error:

1. If I delete or rename “wp-content/w3tc” folder then my website stops working, no page shows except a “hello world”. I think all my posts are stored in this folder. Because when I took the zip backup, its size is 13MB.
2. If I try to edit any lines related to W3TC in my .htaccess then also same problem. (Website stops working, except “Hello world” and login page doesn’t accept my password.
3. I try to delete or rename the plugins folder, then also same problem. (Website works but log-in page doesn’t accept my password)

Whenever I try to log into my dashboard using following link:
http://mrunal.org/wp-admin/

then it automatically redirects me to following link, and my username/password doesn’t work in it.
http://mrunal.org/wp-login.php?redirect_to=http%3A%2F%2Fmrunal.org%2Fwp-admin%
I think the problem is ^because of this.
Because earlier my login page’s title tab would say “Mrunal>Login” but in above link, the title tab says “Onerev>Login”.

Editing / Replacing htaccess doesn’t help

If I try to replace the present .htacess file with an old backup .htaccess, then also my site stops working and shows only one “hello world” page, all the other pages go missing. I think it changes the structure of permalinks.
Where does wordpress save the posts, in my public_html directory? Because it seems at the moment, they’re stored in the “wp-content/w3t” folder and that’s why older htaccess doesn’t work.

What do I wish?

1. I want to log into my dashboard.
2. Then I’ll delete the W3 Total cache from the dashboard. If I try to delete W3TC manually from my hosting account / FTP, then my whole site stops working. 🙁
3. please tell me what to do. I’m really frustrated.

Thanks for reading this lengthy post, you’ll be in my prayers whether you can help or not.