Is your problem a "rainbow screen" see Colored screen when booting raspbian from noobs
This suggests various troubleshooting options. I had a similar issue when I first got a Pi which I fixed by adding a file called config.txt containing “hdmi_edid_file=1″ to the SD card before you first boot it (after copy the NOOBS files onto it).
It is unclear from your question what system you have. It is relatively easy to check the boot partition in OS X, Windows or Linux.
I think the issue has since been fixed in NOOBS. I really don't understand why NOOBS is recommended. Most people only use it to install Rasbian. It is no harder to directly install this, and doesn't waste ~2GB of your SD Card.