Here is a look at a few troubleshooting methods if iTunes could not connect to the iTunes Store.
iTunes is a unique piece of software in that it both stands alone as a media player and is a tool to connect to the iTunes Store and the App Store so that users can purchase content. This service has become part of the conerstone of Apple's business plan for the iPhone, iPad, and the iPod Touch, and without this connection you may not be able to download the latest song or check out what iPad apps are out there. Here are a few ways to troubleshoot the problem if iTunes could not connect to the iTunes Store.
The iTunes Store should be accessible by selecting it from the panel of options in the left hand panel of your iTunes player. Once you select it the appearance of the store with the available departmental options should appear in the central panel. You are going to notice that if this fails it may or may not indicate a software problem that accompanies it, but this will almost always be the case if your iTunes software is not up to date. This may not cause issues if you are just behind on one of the lower level updates, but if you are behind on a full version then you will need to update your iTunes software to solve the issue.
If you are looking for the iTunes update then you can easily do this internally. The likelihood is that you will be prompted each time you open iTunes to update the software, but it may not appear if you have selected to ignore it. If this is the case, you can get the the update by going to the Help option in the upper task bar and then selecting the Check for Updates option. This will then check to see if an iTunes updates exist and you will be prompted to accept it, and then the process for software updates will begin and may include other software that your Apple system has available.
If iTunes could not connect to the iTunes Store on your older version it may have had problems from the start, and this was common with certain versions such as iTunes 9.1.
KeyChain First Aid
Apple has often noted that situations where iTunes could not connect to the iTunes Store could come from issues with your keychain, and a simple repair may be enough to troubleshoot the issue. KeyChain First Aid is the standard location to try fixing this issue and will be used to check on your keychain as well as to fix problems that may be occurring. Go ahead and open KeyChain Access out of your Mac's Utilities section and then choose KeyChain First Aid. Once you have entered your username and password you will be able to choose it and verify, which will then outline any problems that are here. The Repair function is built to fix some of the more standard problems that occur that will not require any outside assistance. Once in here you will want to make sure that your password information is entered correctly, but if you were able to get into KeyChain Access at all then this should not be the primary issue.
iTunes on Windows
If you find that iTunes could not connect to the iTunes Store on your Windows PC there are a few different places to turn to try to troubleshoot the problem. If you find that the network connection times out when you are trying to connect to the iTunes Store try making settings changes in Internet Explorer itself. Go to the Tools drop down menu in Internet Explorer and choose Internet Options from the bottom. Go to Connections from the top tabs and then choose LAN Settings. Once in these settings uncheck the 'proxy server for your LAN' option.
The standard Windows Firewall may also be to blame if you iTunes still can't connect to the store. Go to the Control Panel and find the Security Center, then opening up the Windows Firewall. Go to the middle Expectations tab and then check the iTunes option from the list of approved programs for the firewall to allow.