after upgrading from 2.6.28. 14 to 2.6.28.15 linux will only start in text mode
 

If i try sudo startx i get
xauthority : creating new authority file(not).xauthority
exec:sudo/usr/bin/X11/x.
giving up
xinit : no such file or directory (error2)
xinit : no such process (error3) server error

Shouldn't it be called exec:sudo/usr/bin/X11/X

No matter, it shouldn't have to do something with Kernel upgrade.
And subversions of the kernel are only bugfixes and shouldn't make trouble.
I'm not a friend of upgrading only the kernel of a system that relays on the old kernel version.
So only install a new version of your distribution. You never know what you will do with your system e.g. compiling something.

But to your problem:
- make sure you copied the configuration file (/usr/src/linux-old/.configfile) of the old kernel to the new kernel
- set the link /usr/src/linux to the new kernel directory.
- make the new kernel - if you get asked for some new options discard them
- make modules_install
- never make headers_install
- if you have installed some drivers e.g. a graphics driver, reinstall it, them.
- copy the new kernel to /boot/vmlinuz-test
- make a new bootloader entry for that kernel
- reinstall the bootloader if needed
- reboot

Following these steps should be normally a save thing.

Sorry I took so long too reply with home computer down have too check at work will print and try later
once again Thank you
Maurice