Is there some or other way to get your Raspberry Pi back to the way it was when you first started it up?

Sorry about my way of writing everything.

I used Debian Wheezy and I installed it via a pre-installed SD card that you can buy from rs components.
Oh and the page I got it from was in chapter five:Partition Management.

After i posted the topic i cleaned up my raspberry pi and the warning was gone so my startx worked. When i got into my desktop i followed a piece in the raspberry pi user guide to re size my partitions but after i did that i restarted my raspberry pi and when it went on again the screen was blank an...

When I start up my Raspberry Pi it goes through its normal list of start ups and then for the last few days it has been showing [warn] Root filesystem has insufficient free space mounting tmpfs on /tmp ... (warning) Then after i logged in and type in startx the screen goes blank and then i'm back wh...