Hi there, is this your particular laptop keyboard? http://www.notebook.de/bilder/products/d3/47540_d3.jpg
If so the 'print screen button' is the secondary function of the 'END' button located above the / on the numpad, usually activated by pressing FN + the key in question.
As for an alternative it depends on what you want to get an 'image' of. you could print a website to the 'Microsoft xps document writer' which will create a picture file of the website you are on as if you had printed it, or as the person above mentioned you could use the snippet tool
You can also try the following:
Click on Start > All Programs > Accessories > Ease of Access > On Screen keyboard > Prt Screen.
^ this works if all else fails