If you feel fit and safe enough to climb a ladder, it is possible to use one when cleaning the windows on the ground floor or upstairs. To make it safer – and to avoid damage to surfaces – fit ladder feet covers.
However, an even safer option is to clean your windows with a mop on a telescopic pole plus homemade cleaning product. A 16-17ft extendable non-professional pole (widely available online) will enable you to reach upstairs windows too. This way there is no risk to health from balancing on a ladder or from causing damage (for example by dripping dirty water on your skin).