wordpress localhost error

[klingding]

Warning: require_once(C:\xampp\htdocs/admin.php) [function.require-once]: failed to open stream: No such file or directory in C:\xampp\htdocs\wp-admin\admin.php on line 12

Fatal error: require_once() [function.require]: Failed opening required 'C:\xampp\htdocs/admin.php' (include_path='.;C:\xampp\php\PEAR') in C:\xampp\htdocs\wp-admin\admin.php on line 12

looks like i'm missing an admin file. how do i fix this problem? any detailed help greatly appreciated.

[Altrea]

looks like i'm missing an admin file.

No, looks like you have done something wrong in the wordpress installation dialog, where you can define the base path.
Or any change that causes this issue.
Seems like your wordpress don't search the admin.php file in its wp-admin folder.

how do i fix this problem?

Install it correctly, or undo the changes which causes this issue.