I bought a brother tn450 toner cartridge replacement yesterday, but I haven never reset it before. Any suggestions?

I have never heard of resetting a toner cartridge. You just remove the old one and put in the new one. The cartridge should come with a sheet showing how. If not, you can probably find instructions on Brother's web site.

There are a bunch of YouTube videos

https://www.youtube.com/watch?v=DdTwJxOwcbo

But this is from there website

Reset the print server to the default factory settings. | Brother (http://support.brother.com/g/b/faqend.aspx?c=au&lang=en&prod=hll2340dw_us_eu_as&faqid=faq00000105_031)