Hi...

while installing Mythtv, a message came up:

Failed to connect to database: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) at -e line 5, <> line 1.
Failed to create database (incorrect admin username/password?)
If you supplied incorrect information, try:
dpkg-reconfigure --force mythtv-database
tobias@TBK-Ubuntu-Laptop:~$

It says something with an invalid password or username, but I haven't set any username or password for mySQL.
mySQL is not my cup of tea...

can somebody help me?

You have to set up a root and user password first:

mysqladmin -u root password 'root password'

(this will be the mysql root password for mysql administration)

Then set up a user:
Run the mysql client
mysql -u root

Now in the client enter something like:
grant all on db_name to umagarz@localhost identified by 'user password';
quit
(enter the name of the database you have created in place of db_name)
If you haven't created a database yet you can do that first with:
create db_name;

Now you will have a mysql user accout with the password you entered.

You can start the mysql client now with:
mysql -p <db_name>

Be sure to enter your username and password in any script with which you connect to the mysql server.