Wont initialise tells me it wont initialise with code 0xc0150002 all is installed and steam account set up and working

The code relates to EXPLORER.EXE not loading properly or being corrupted.  This occurs after some Windows updates, etc.  If you have just recently done an update (Microsoft Windows Update KB923191) there might be some ways to recover from this.  
First try, copy working EXPLORER.EXE from another system (same operating system and version) and try overwriting EXPLORER.  If that doesn't work, there are other more complex solutions, with varying degrees of success.
If possible, try to copy all of your *important* data from the disk (even if you have to physically transfer the hard drive to a working system and copy it) *before* you start fooling around with overwriting Windows files or any major repair like this.
I hope this helps,
Ken