If a non-admin user needs to access Item records, the role of the user must have the Items permission first with necessary access level. See steps below to be performed by an Administrator.
1. Navigate to Setup > Users/Roles > Manage Users.
2. Edit the role of the user.
3. Navigate to Permissions tab > Lists subtab > add Items and set Access level.
Note: For more information about access level, please see Access Levels for Permissions
4. Click on Save.