Well for some odd reason my Minecraft refuses to create/launch worlds for singleplayer and cannot connect to multiplayer servers. This is only an issue on Version 1.7.2

Are your video drivers and Java up to date?

Also, if you are running a 64bit Operating System, make sure you are using 64 bit java.
GG wrote:

As I've said before, you can't connect to multiplayer servers because the build that almost all of them run on (craftbukkit) is still in the process of releasing its 1.7.2 version of the build. Thus, the only multiplayer servers you could connect to are 1.6.4 craftbukkit servers that people have protocol-hacked to work with 1.7.2 (these servers have no 1.7.2 features, they are just glitched to allow 1.7.2 clients to connect) or vanilla servers running on Mojang's release.

As for your single player issue, it could be a variety of things. You need to click the option to keep your client side console open while running minecraft, and then copy and paste the logs of what is occuring when you try to create a world.

Try deleting your entire .minecraft folder (keep your saves and server info if you'd like), then re-install it.