505 Server Error

[AngelinaBaby]

I am using prestashop version 1.6.5. though my store was working all fine, a few days ago i was testing a new (separate) website on same hosting account, i just moved the prestashop store folder to a subdirectory and then moved it back to its original location. But since that every time a try to access my store it is displaying  this 505 Server Error

Notice: tempnam(): file created in the system's temporary directory in /home2/username/public_html/store/classes/PrestaShopAutoload.php on line 151

Fatal error: Uncaught Error: [] operator not supported for strings in /home2/username/public_html/store/classes/db/DbQuery.php:70 Stack trace:

#0 /home2/username/public_html/store/classes/ObjectModel.php(203): DbQueryCore->from('shop', 'a')

#1 /home2/username/public_html/store/classes/shop/Shop.php(131): ObjectModelCore->__construct('1', NULL, NULL)

#2 /home2/username/public_html/store/classes/shop/Shop.php(392): ShopCore->__construct('1')

#3 /home2/username/public_html/store/config/config.inc.php(97): ShopCore::initialize()

#4 /home2/username/public_html/store/index.php(27): require('/home2/username...')

#5 {main} thrown in /home2/username/public_html/store/classes/db/DbQuery.php on line 70

 

Any help will be highly appreciated