Can I reload OS X 10.9.3 safely? ISSUES: •Cannot Cut

Question

Can I reload OS X 10.9.3 safely?   ISSUES: •
Cannot Cut & Paste in iWork 09 or MS2011 •
Cannot Print in solid Black but can print colour and greys •
Command, Option, Control and fn keys cause gibberish instead of correct fonts to display or print  I am having issues that are the same if I use iWork 09 or MS2011 and cannot cut and past from Safari or indeed any other application to a Pages App document or Word document.  Also, the Command, Option, Control and fn keys, when left on accidentally, when they did not before some upgrade as they are typing gibberish and sending emails before I have pressed Send, which has been causing serious business problems of embarrassment.  I find much has slowed up in response times and is not slick in operation speeds.  It has slowed down but I have not noted if any particular update caused any of these changes or degradation except other than when SAFARI was upgraded on 20 June my HP Officejet 7500 E910  is not printing in BLACK.  I have tried the standard practice of turning unplugging power, then USB cable etc and it prints in colours but not solid black and will print in GREY VERSIONS of BLACK.  Computer Model - iMac 21” 2011:  3.06 GHz Core i3 Processor with Memory of 12 GB 1333 MHz DDR3

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.
Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a Fusion Drive or a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.
The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
Test while in safe mode. Same problem?
After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.