Imagine a toolbox of tools. When you are young, you fill it with what you need to get a job done. Over time, your toolbox gets full enough that you can do every task with your current tools so you don't buy more. Ten years later, all your tools start dying at the same time and you have a huge cost to replace them all.
When you learn .NET 2.0, you put a lot of .NET 2.0 tools in your toolbox. You probably didn't take time to add the .NET 3 tools to your toolbox or the .NET 4 tools in your toolbox (WPF, WCF, LINQ, XML Serialization, etc.). Now .NET 4.5 is coming out and you need to update your entire toolbox.
All I can say, is you have caching up to do. The problem isn't that you are too old to learn, it is that you have such a lot to learn it seems overwhelming. When you were young, you didn't know everything you needed to learn, so you didn't have that overwhelming feeling. You couldn't see the hill you were climbing. Now you are older and you understand what you don't know. Now you see the hill you are climbing. It isn't any bigger, in fact it is likely smaller, but you can see it so it is daunting.
You need to take two hours a week to learn as part of your job. If you do this your toolbox will fill back up with new tools and you will never find yourself in this situation again. Don't worry about your company losing those two hours to your education, they will gain so much more. You will be more productive and something that would have taken two days, takes you a few hours. For example, my previous company I joined a team that had spent over a month working on custom code to build an XML file only to find it didn't work with WPF and binding. I learned XML Serialization and recreated their entire code in eight hours (code that took them a month). I didn't do anything impressive. I didn't write the XML serialization technology, MS did. My code involved simple classes that any new college grad could have done. I just added a new tool (XML serialization) to my toolbox. If they had added XML Serialization to their toolbox and used it, they wouldn't have wasted a month on code that didn't integrate. So you see, your two hours of self study a week will pay off big for your company and is a wise investment.
What should you do to start? Well, since you are a .NET Developer, go with this:
Learn WPF and LINQ: http://windowsclient.net/learn/