Which One Should Be Used?
Both 'with regard to' and 'in regard to' are correct and can be used. Both can be used to mean 'regarding.'
With regard to
'With regard to*' is used to convey 'concerning' or 'regarding.' It is more common than its other form 'in regard to.' Have a look:
In regard to
'In regard to' is also used to mean 'regarding' and 'concerning.' 'In regard to' is correct but it is less common than 'with regarding to.'
He said he has nothing to say
'In regard to' and 'with regards to' with the s connected to 'regard' is a common case of misspelling. They are incorrect forms but are often mistaken by even natives.