Regular Expression

Could somebody point me in the right direction. I am cleaning up my tags and I have lots of tags that have the following stuture

01 - Filename
344 Filename
. Filename

  •  Filename

Are there expressions which will clean the tags up to leave just the filename.

Where can I learn to write expressions?

Thanks in advance for you help

If you have tags (fields) with those structures and want the values to be equal to the filename, then you don't need to use a regular expression. You can just set the tag to the filename using a format value action.

Thats ok with a small number of the tags, but the majority have the title or artist missing thats why I need an expressions

It's hard to tell what you're trying to do. The following site is a pretty good guide to regular expressions.

An expression is tailor-made to fit one particular pattern. So it would be much easier to point you into a direction if you could supply examples as close to reality as possible.

E.g. if you have a TITLE that looks like this:
344 Filename
you could apply an action to remove the 344 with a replace action.
If you have a TITLE that looks like this
01 - Filename
you can perform an action of the type "Guess values" and the pattern
%track% - %title%.
But this is just guesswork. Please be more specific.