I have Ryobi RBL30MVB Blower\Vac\Mulcher. It Vacs and mulches but does not blow. It did blow the first time I used it but not since. The plastic handle mechanism for moving from suck to blow seems

The hose can be flushed out using a garden hose. The problem with wet vacs not sucking into the bucket is the float ball sticking. It rises and seals when the bucket has reached its fill level. This stops water reaching the motor.

hardware stores or anyplace that sells shop-vacs

there is none
check the unit for broken lead wire , or burnt motor . They have a problem where the blower fan runs on the housing and melts or welds together , stopping tye motor from running

Sounds like a bad switch. Possibly a loose wire.

The best thing for a basement that is vulnerable to flooding is a small sump with a permanently wired automatic submersible pump in it. Such pumps are relatively cheap and available in many qualities.
While such an installation will not keep a basement dry it will ensure the water level rises only enough for the majority to flow into the sump and be pumped away without you needing to do anything.

Wet vacs of my experience either have a float valve to prevent water ingress into the motor or a switch to cut off the power if the level rises too high.
Many such vacs have a powerful motor generating much heat and are only suitable for fairly short duty cycles. When used continuously the internal heat build up can distort plastic and melt thermal safety fuses.

It is impossible to guess what the trouble might be and that will only be revealed by checking. With vacs the first suspect is the power cord and the second is the switch...

Unlike the old days few vacs today have a blower facility.
In the old days many vacs used a single exhaust port the hose could fit into for blowing and in particular using some of the supplied accessories - such as the famous spray gun loved and hated by everyone in equal measure.

Modern vacs tend to have a diffused exhaust usually through several ports, perhaps because of imagined safety concerns. I suggest you check the operator instructions.

Most Shop Vacs allow you to hook the hose up to the output valve as well as the intake.

Make sure that your hose is hooked up to the intake valve on your shop vac.

To PETMOMBR I recently had the same problem, I contacted Emerson Tool Co to see if a replacement for the blow wheel is available,and sadly it is not. I was told that the Rigid vacs do have replacement parts and some with a lifetime warranty.
Had my vac for approx 10 yrs, I would say I got my moneys worth. In all, I'd say it's a toss, time to get a new one.
Doghairsucker in Glendora, CA

Most wet dry vacs have a ball float that blocks the vacuum when it is full of liquid. Yours sounds as if it is full or the ball has gotten stuck in the up, or blocking position.

I don't know about Ryobi, but I did purchase additional hoses for my Rigid vac for the same purpose