If you pick up a ballpoint pen that you've not used for some time, try to write with it but it won't work despite there being plenty of ink left in it, then don't just chuck it in the bin!
This is usually caused by the ink in the nib becoming hard. If you hold the very tip of the nib in some very hot/nearly boiling water for a few seconds, this will melt the ink nearest the tip and you will find the pen will write okay again.
This is especially useful if it is one of the more expensive ballpoint pens with refills that cost �2 or more!
Tipking says... Don't just dip the pen into a kettle. The reason for this is the ink can flow out and you don't want you tea and coffee turning blue.
