Rats. If the windows are timber, you should be able to chip out the dried putty and remove the glass. You could have a go at puttying it back in yourself, too. PAL Glazing Compound - Fillers | Mitre 10™
If you DIY, follow the manufacturers instructions around letting the putty dry and then be sure to paint it to protect it.
Example YouTube video that I have not vetted. You should be able to leave/keep the glass intact with a bit of care (says the man who has never done it). https://youtu.be/ePCIWeUBwLI