try this ?

1. Open your FTP browser and navigate to the folder/directory that you installed WordPress in. From there, locate ?wp-config.php?. You?ll need to open it in whatever editor you like. Once you?ve done this, enter the following code somewhere close to the top:
@ini_set('memory_limit','64M');
Check to see if the error is resolved. If not, go on to step 2.
2. In your FTP browser, navigate to your root folder (it?s usually /public_html/ or /www/) and look for a ?PHP.ini? file. You?ll need to find a line like this:
memory_limit = 12M
Change ?12M? to ?32M? to allow the PHP scripts WordPress runs to access more memory. If this doesn?t work, try changing it to ?64M?. If you still have issues, and you have access to your webserver, it might be necessary to restart your webserver. If this doesn?t work, or you don?t have access to your webserver, then you?ll need to go ahead to step 3.
3. We?re going to edit your /install.php file. You can find this file in the root directory of your site, or in whichever directory/folder you installed WordPress in. You?ll need to add the following line to the beginning of the file:
ini_set('memory_limit','32M');
When you are finished, the beginning of the file should look like this:
ini_set('memory_limit','32M');
/**
* WordPress Installer
* @since unknown
* @var bool
*/
define('WP_INSTALLING', true);
If this still doesn?t work, try changing ?32M? to ?64M?. If you?re totally at a loss for ideas, I?d recommend contacting your site?s host and asking them if there?s any issues with your server. If you have access to your administrative control panel, you might want to try disabling any extraneous plugins, as well.