Well, I'm not surprised - your regex doesn't match your input...
Your class delimiters are not the same - double quote and single quote are not the same character; "onload" is not the same as "önload"; there is a semicolon at the end of "img_onload(this);" instead of after the double quote, and so forth.
Seriously, I wouldn't parse HTML with a regex: it's a silly idea. Instead try using a HTML reader which will process the input as HTML and provide lines, attributes, and so forth in a much mopre friendly and reliable way.
A quick google will find you loads of them here:
https://www.google.co.uk/search?q=HTML+reader+codeproject&oq=HTML+reader+codeproject&aqs=chrome..69i57j0l5.6613j0j7&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8[
^]