Helping people with computers... one answer at a time.
Restore points are a handy way to undo problematic system changes. Even though you can control it some, restore points can only go back so far.
I want to restore my Windows XP laptop to a previous restore point but when I go to system restore I only see this month's. Where did all my other restore points go? System Restore is turned on, and I've set the system restore point disk space to maximum.
In short - because System Restore can only remember so much.
Unfortunately people's expectations are often otherwise.
System Restore is really intended as a kind of "short term" safety net. By that I mean that if you make a change that destabilizes your system, you should be able to quickly tell, and then use system restore to revert to the way things were before that change. The common scenario is that you realize that quickly; often within minutes of having made the change.
System Restore wasn't really intended to be able to restore you back to any arbitrary time in history. It has limits. Limits you can control, somewhat, but even then there are limits.
Each time a restore point is created, Windows saves a bunch of information related to the state of your system at that moment in time. That "bunch of information" takes up disk space. Since system restore is documented as "created daily and at the time of significant system events (such as when an application or driver is installed)", they can add up.
That's where the limits come in.
Right click on My Computer, click on Properties, and then click on the System Store tab. Make sure the Turn off System Restore checkbox is not checked. (Uncheck it if it is, and click on Apply.)
Click on your C: drive in the available drives list, and click on Settings...
Here you can see, and control, the amount of disk space allocated to System Restore. In my case a maximum of 12% of my disk space is made available.
If the space required by System Restore exceeds the amount available it will start deleting the oldest restore points. If your restore points aren't going back as far in time as you expect, that's probably exactly what's happening.
You may want the disk space set to its maximum to keep as many as possible, but you still can't keep them all. The only way to truly keep that kind of backup information for a long time is to:
Use a true backup or imaging program
Keep the backups on off-line media like CD-ROMs, tape, or even external hard disks, so as not to run out of room
With a good backup or imaging program you should be able to restore your entire machine to any arbitrary date for which you kept the backup.