What makes you so sure that it's just a driver problem?
When Microsoft Office applications won't open (or any other application for that matter) it is very rarely, if ever, caused by a bad or missing driver.
Missing drivers usually cause hardware problems, not software problems, but if you're convinced it's only a driver problem you can download them from Lenovo Support. Go here and choose your country if it's not the UK: http://support.lenovo.com/en_GB/
If installing Lenovo drivers doesn't help, I suggest you back up your data to a second hard drive or external hard drive, then perform a factory recovery.