I had some error in my new wp theme. When I enabled the new theme, I got a blank page. I was unable to access my wordpress blog both from frontend and backend (admin panel).
In this case, either I need to change/fix my theme’s code. But, what if I am not a coder?
The solution is to change the currently active theme from database.
Open phpMyAdmin, go to your wp database. Open wp_options table. Search for three option_name – template, stylesheet, and current_theme.
SELECT * FROM wp_options WHERE option_name = 'template' OR option_name = 'stylesheet' OR option_name = 'current_theme';
See the option_value fields from the search result. The option_value will be your theme name. Change option_value of the search result to ‘classic’ OR ‘default’. Classic and default are the default wordpress themes present at the time of wp installation.
UPDATE wp_options SET option_value = 'default' WHERE option_name = 'template'; UPDATE wp_options SET option_value = 'default' WHERE option_name = 'stylesheet'; UPDATE wp_options SET option_value = 'default' WHERE option_name = 'current_theme';

Genial fill someone in on and this fill someone in on helped me alot in my college assignement. Thank you seeking your information.
Thanks, helped me a lot!
Thanks this help me today.
ur information is more useful to me but 80 % i reach to success but remaining 20% creating problem can u sort out me frm this. i m not able to change d theme
Thanks a bunch, got the white page myself today after changing themes & this definitely helped me out.
THANKS A WHOLE LOT!!! iT HAD FREACKED ME OUT!!! Figured it out and I am a COMPLETE newbie on pHp…but please refine the steps a bit for them to be clearer…like what tab to click…what to put where…like replacing the theme name to “classic” etc…I followed it but am sure a whole lot of other people will be stuck..trust me!
Thanks again!
Thank you very much for this info!
Thanks man, you saved my site!