If you've got UPVC windows which are normally double glazed, or double glazed windows you'll need to get a specialist in to do the job. There are plenty in the yellow pages or you should find a shop locally.

For a single glazed window in a standard wooden frame(sash or casement)you should be able replace the glass. They will be glazed from the outside with putty.

From the outside remove the broken glass by removing the old putty with a hammer and an old chisel. NB be careful you should find a few small nails which were holding the old pane in place.

With the glass out make sure you chisel out any putty residue.

Next measure the hole you have created so you can buy some new glass cut to size. Make sure it's a mm or two less so it will slot in with ease but not so small that you can see any edge from the inside.

Window glass is very cheap you local glass shop will cut you some to size at a very reasonable cost. They usually also supply putty. By a small tub enough for the pane you buy.

The new pane needs to be bedded in. With your thumb apply a thin bead of putty round the back edge of the frame which the new glass will sit against.

Carefully press the glass onto the putty. It should create a good seal all around the glass.

Gently hammer in several panel pins to hold the glass in place whilst the putty is drying. One or two on each of the four sides will usually be adequate.

Next go round the glass with more putty to cover all the outside edges

With a putty knife smooth it out at an angle to match adjacent windows.

Trim off any surplus on the inside to.

Tip You may find when you're doing the final smoothing the putty tends to drag a little on the putty knife and spoil what you've done. Try a little vegetable oil on the putty knife and it won't drag .

NB putty is very oily and takes ages to dry, weeks sometimes. Wait until it has gone hard before painting otherwise it will start to wrinkle up.