need
-root explorer
-whatever font you want. the regular version and a bold one.
in root explorer press the mount button at the top right so that it says mount r/w instead of r/o. navigate to whatever font you want (it would help if they were in the same folder). rename the regular version "Arial.ttf" and name the bold version "Arial-Bold.ttf" both without quotes, of course. then hit the menu soft-key, choose multi select, and then tap both of those files to choose them. then hit copy and navigate to /system/font folder (make sure it is mounted r/w). now you will hit paste. once you've done that you'll see the two arial fonts will have different permissions than the rest of the .ttf files in the folder. long press each one (one at a time) and change permissions to user: read, write; group: read; others: read. it will end up looking like this rw-r--r--
and there you go, you've successful changed your system font. reboot the phone and you're done.
Try 'Font Installer' in the market.hmm..... sorry dude. i'm not sure why that would happen. i've done it a bunch of times without fail.
hope you had a nandroid! if not, then turn the phone off, boot into recovery, data/cache wipe and install any rom you have on your sd card. that'll at least get your phone working.
trial and error, my friend. trial and error...
The bold file needs to be replaced with a genuine bold font. If you replace it with a regular font you will get boot loops.I searched and I found a post about this issue, and the poster had the same problem I did; it only worked for them when replacing Arial.ttf or clocktopia.ttf ONLY for some reason. I tried that and it worked, but whenever I changed both Arial.ttf and Arial-Bold.ttf, I got a boot loop again lol.....very weird!
um there is actually a much easier way now with the latest release in theme manager it allows you to change fonts