Hi @ajnog ,
It could well be a hardware problem. Intermittent problems doesn’t have to mean totally not working any more e.g. loose connections or dry solder joints etc, sometimes work and sometimes not.
Try connecting a USB keyboard to the laptop and check if there are any problems when using it.
Here’s a [https://support.lenovo.com/au/en/solutions/ht103985|checklist] from Lenovo to try and narrow down the problem.
If it is determined that the problem is in the keyboard (were any liquids spilled on it at all?) here’s the [https://download.lenovo.com/consumer/mobiles_pub/s145_series_hmm_201902.pdf|hardware maintenance manual] for the laptop. It shows the necessary pre-requisite steps and then the procedures to remove all the components. The keyboard is part of the upper case assembly.
Usually it is preferable to replace the keyboard rather than to try and fix faulty keys as you can create more problems than what you has when trying to fix them.
Here’s a link to the [https://pcsupport.lenovo.com/au/en/products/laptops-and-netbooks/ideapad-s-series-netbooks/s145-14iwl/81mu/parts/display/compatible|parts] for your laptop.
Click on ''Select Commodity > C-cover with keyboard (90)'' to find the part numbers for all the ''country specific'' keyboards available for the model. Once you have found the part number applicable to your particular model, search online using the part number ''only'' in the search box of your browser to find suppliers of the part. usually the part number is printed somewhere on the underside of the upper case assembly if you wish to verify that you’re ordering the correct part.