Before change make copy DB and replaced files!
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Variant 1
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Step 1:
Download -> http://webfile.ru/1078892
Step 2:
Copy dumper.php in a root of a site.
Step 3:
Come under the reference www.yoursite.ru/dumper.php
Enter a login and the password.
Step 4:
Open a file shop_2006-08-28_17-20.sql, and replace CHARSET=cp1251 on necessary to you. Save.
Step 5:
Copy shop_2006-08-28_17-20.sql in a folder www.yoursite.ru/backup/
Step 6:
Refresh page www.yoursite.ru/dumper.php
Step 7:
Choose "Restore", choose Base, and from the list choose shop_2006-08-28_17-20.sql
Press button "Restore"
Step 8:
Copy on a server system/index.php and admin/sections.php and admin/templates/koobi4/sections/section_show.tpl
...
All should work