Can't access wordpress with MAMP

I’ve been designing a couple of websites on my Mac using MAMP as my local server, it has taken quite a few months since I do it on my spare time. Today I was hoping to work on them and what was my surprise that I could not access either one. I have tried a million different things.
I do get the MAMP: It works! page, but when I go to wordpress most of the time I get the message:
“Not Found
The requested URL /wordpress/ was not found on this server.”

I checked the wp-config.php file. I changed it’s name so that wordpress would recreate it. At some point I managed to get a strange looking login page but it didn’t recognized my login name and password. This would take me either to the Not Found screen, or at some point I got:
“Error establishing a database connection
This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at localhost. This could mean your host’s database server is down.
Are you sure you have the correct username and password?
Are you sure that you have typed the correct hostname?
Are you sure that the database server is running?
If you’re unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums”
(I have my database name correct, root, root, and localhost)

No, I did not forget my password, I’ve been using it for months. Still I followed some instructions to change my password in the database in MAMPs phpMyAdmin window. That didn’t work so I went back to the previous version of my database.

I also tried reinstalling WordPress by substituting a newer version and updating the wp-content folder. That took me to a screen that said:
“Already Installed
You appear to have already installed WordPress. To reinstall please clear your old database tables first. “
(I don’t want to lose my database, so I don’t know if there is anything I can do in this respect)
I also installed the newest version of MAMP and then decided to go back to the old version in case that was creating problems, but it didn’t make any difference.

I am desperate. I do not want to lose months and months of work. I haven’t even published my website yet. I usually browse the internet and ready other people’s posts and find the answers to my problems. This time I’m at a loss.