Theme's Coding Problem turn down our website

Hi, I recently changed the fuctions.php code, and surprisingly found out our website cannot be viewed or login. When I clicked the go back button, it showed :
Parse error: syntax error, unexpected “<” in D:\Hosting\11752070\html\wp-content\themes\u-design\fuctions.php on line 1587

And I did ask the host for help, after that our website’s login page turned to as below:

Warning: include(./wp-admin/includes/class-wp-admin-list-table.php) [function.include]: failed to open stream: No such file or directory in D:\Hosting\11752070\html\wp-admin\index.php on line 8

Warning: include() [function.include]: Failed opening ‘./wp-admin/includes/class-wp-admin-list-table.php’ for inclusion (include_path=’.;C:\php\pear’) in D:\Hosting\11752070\html\wp-admin\index.php on line 8

Warning: require(D:\Hosting\11752070\html\wp-admin/wp-blog-header.php) [function.require]: failed to open stream: No such file or directory in D:\Hosting\11752070\html\wp-admin\index.php on line 17

Fatal error: require() [function.require]: Failed opening required ‘D:\Hosting\11752070\html\wp-admin/wp-blog-header.php’ (include_path=’.;C:\php\pear’) in D:\Hosting\11752070\html\wp-admin\index.php on line 17

Can anyone help me ? I am so upset~~~