You need to define "a lot". $20k? $200k? $2M? $20M? The answers would be very different.
This is a case where your best bet is to leave it as is, in whatever investment vehicle, until you've educated yourself. If you're not a savvy investor, there are financial planners who can help you. When my sister's husband got a large medical settlement, her lawyer sent her to a planner. Sis ran his advice by me (I'm more of an investor than she is), to make sure she was getting sound advice.
A couple things you need to be careful of:
If you've received an inheritance that's in retirement accounts, there are rules on withdrawals and taxes may be owed. Do NOTHING until you understand this.
If you've inherited because you've lost a loved one, do only the minimum for a year. A lot of people, in their grief, make bad decisions. Leave the money alone for a while--it'll still be there.
You need to look at your overall financial picture, not just a stand-alone windfall. Do you have kids going to college? Is your retirement set? Do you have debt? Some "standard" advice, like paying off your mortgage, might not be the right choice for you (if the payment is manageable and you've locked in a low interest rate, for example).