I'm just going out, so if it is The Foggy Dew and you want to find the piano sheet music online, this is my trick:

On Google or similar, do a search for

The Foggy Dew piano sheet music

Then when the results come up, click on the Image tab and it will show pages from sheet music which is available online. Some of them are free, some are for sale. The advantage is that you can see which key the music is in and choose the one you want.