If that language has multiple keyboard layouts associated with it, then you may want to change the keyboard layout. Then under the heading 'Preferred Languages' click 'Add a language' and add the language you want. Go to Windows Settings>Time and Language>Language.

Don't worry, you won't find your Windows menu language change to it if you do this. If you want to install another keyboard layout, you will need to install the language associated with it in Windows. You may also find that your laptop keyboard either lacks a key or has it in a weird space e.g.

The alternate keys could be typed with either 'Alt' or 'Alt Gr' depending on which side of the keyboard they appear on. For a better view of your keyboard layout search for the website 'kbdlayout'. Choose the layout you want to type in, then just type in the textbox and watch the characters appear as if you had that keyboard layout enabled on your device. You can check out and try most keyboard layouts in a web browser by searching for and going on the websites 'gate2key' or 'branah'. That being said, using this key can be a bit clunky so you should consider installing and learning a keyboard layout suited to your language. However, if I use the 'Polish (Programmers)' keyboard then 'Alt Gr' + 'a' gives 'ą'.

If I use the 'English (United Kingdom)' keyboard then 'Alt Gr' + 'a' gives 'á'. Remember that the letter that appears on screen depends upon the keyboard layout currently used and you can switch between multiple installed keyboard layouts using 'Win' + 'Space'. You don't need to change/install another keyboard language or layout. The accents printed on the keyboard should work when you hold 'Alt Gr' key which is to the right of the spacebar.

E with an accent mark alt