Macbook Air Causing Problems

Virtually all the posts on this blog have been written on a Macintosh computer, first on our iMac, a large-screen, desk-top model, which sits on a desk in the corner of our bedroom. It is now somewhat redundant, having been purchased in around 2007. It has become very slow, needs up-grading with the latest operating system, but I doubt very much that it will work on the most up to date version of the OSX operating system. So I transferred to using Carol's MacBook Air, which she purchased through Milton Keynes Academy. It has worked perfectly well up to now, but it did have a slight hiccup when it refused to start up a couple of months ago but it seemed to right itself after a day or so. But a day or two ago it simply refused to open and all I get is a grey screen. It is usually turned off and kept on charge, and then turned on when it's needed, but still nothing. I am now using another laptop, bought by Carol for Academy work, a Toshiba, and I'm managing very well with it. It is a good deal bigger than the MacBook Air, which has an 11 inch screen. All this very annoying because I want to transfer a lot of my writing onto word processing. We also have a Samsung Galaxy tablet computer with a 10 inch screen, but that seems to have gone on go-slow, probably because it is several years also and I realize, like most computers, they need up-grading every couple of years. As such, it has been quietly retired, much like the iMac.