Paging Error :The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must be called before the method 'Skip'

You do have a Skip method.

The PagedList added it for you. Check the code out. That's how paging works, Take and Skip.

Also I think your case statement was meant to be

    switch (sortBy)
    {
        case "Name desc":
            employee = employee.OrderByDescending(x => x.FUllName);
            break;

        default: // Not: case "Default"
            employee = employee.OrderBy(x => x.FUllName);
            break;
    }