what if an employee holds back 3 weeks of income already made. I no longer work there

You likely have a claim for back wages under either R.C. 4113.15 if you area salary employee or under the Fair Labor Standards Act if you are an hourly employee.  If you are a covered hourly employee, you may be entitled to your back wages plus an award of damages equal to the unpaid wages. If you are an hourly employee, and it has been more than 30 days since your last pay was due, you are entitled to your back wages plus damages in an amount equal to 6% of the amount of the claim still unpaid and not in contest or disputed or $200, whichever is greater.