reconnect network

Typically, when you change the network name, you would do so on your Express before doing so on the "main" router. Is this what you did? You should provide a it more information about your current network configuration with your Express. Include the make & model of all of your networking HW and how you have them configured.

had to change network name to connect DVD players.....

So, this means that you changed the name of your wireless network, so you have in effect a "new" wireless network, correct?

Now cannot reconnect my airport express

If you do have a "new" network now, this means that the AirPort Express was originally configured to connect to your "old" network......the one that existed before you changed the name of the wireless network. The Express is still set up with those settings......unless you have reset the Express......so it is still looking for your "old" network.......but cannot find it because it is no longer there.

Or in more simple terms, the Express is now "lost" and it does not know how to find its way.

You need to perform a Hard Reset on the Express to reset it back to its default settings......so that it can be programmed with the new settings that it needs to connect to your "new" network.

Set up the Express to "join" your "new" network just like you did when you set it up to join your "old" network.

Post back if you need more help or tips with this process.