Can not close or delete ticket

For your first issue, try de-activating then reactivating the plugin, and let me know if you can close and delete tickets in the admin panel.

Second, for adding the capability to a user, you’ll need a plugin. This plugin is what I use:
https://www.ads-software.com/plugins/user-role-editor/

After I pressed “Delete query” I replaced to page with address …/wp-content/plugins/wpsc-support-tickets/php/delete_ticket.php?ticketid=2 – it is clear page with one question “Балуемся?” (“Frolic?”). That’s all. Process stoped on this step.

Please answer what table in database can I delete to clearing all data of plugin? I want to try reinstall it from zero.

wp_wpscst_replies
wp_wpscst_stats
wp_wpscst_tickets

I find this:
wp_wpscst_replies
wp_wpscst_tickets
wp_wpscst_meta (need to delete too?)

The table wp_wpscst_stats is absent.

make error in name
wp_wpstorecart_meta – need to delete too?

I reinstalled from zero with clearing of database and deleting of plagin from WP.
Next errors present:
1) User can write and send message but admin cann’t send answer.
2) Admin can make but cann’t save user fields.
3) Admin cann’t delete any message or whole ticket (see above).
4) Admin cann’t close any ticket.

Note: I have last update of WP (3.8.1) and last update of plugin.