I have been learning C# from scratch using a book called The C# Player's Guide. For the most part I found it really good, but as it moved into more advanced concepts I stated to find it less and less helpful. There are some topics where I felt I was basically readying a wikipedia article just giving a cursory explanation of a concept.

I'm looking for more information on Polymorphism, Virtual Methods, and Abstract Classes... Strutcs also.

I would prefer a book to buy and what I really need is something with exercises to practice what it is talking about if possible.

Would anyone have any suggestions for learn programming books that cover these topics in detail?

It's been awhile since I opened a C# book, but I've always gone with the Nutshell series:

C# 7.0 in a Nutshell: The Definitive Reference

Beyond that, MSDN is a great place as well.

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/index

The best way to learn these concepts is by playing with them.

want to learn about polymorphism? Fire up visual studio, create a program with a list of polymorphic objects and step through the code in the debugger. 

Ask yourself what sort of problems might this solve?

One thing to point out with all these new things you are about to learn is they are tools in your toolbox. Each has a problem it can solve and you should always use the right tool for the right job.

There are some older books, usually C++ books if I'm honest, which will use polymorphism and inheritance to solve near every problem, basically using the screwdriver to bash in a nail.

With C# most of the documentation is more modern and avoids such advice, take everything you read as one of many examples and use multiple sources to learn.

Enjoy!