Good day to you. The A100 is a Satellite, but not a Satellite Pro. Additionally, the exact model of your laptop will include a number of characters following the 100. For instance, it could be A100-Sxx11TD (where xx=22, 23, or 81), or it could be A100-STxxxx (xx=1041, 1042, 3211, or 8211). Therefore, it is possible that there could be instructions or other information available for your specific model. However, there are no instructions or other such indication as to how you could replace your own keyboard at Toshiba. They indicate in user materials that an authorized service provider should handle any such matters. I suspect this is because it is much more difficult than it may first appear - a notebook keyboard is not an isolated piece of equipment as it is with a desktop, as it is an integrated part of your notebook.
Unless there is a real need to do otherwise, if you can not rectify the issue with your keyboard, I would recommend simply obtaining and using an external keyboard. There are a number of different models specifically designed to be small and portable for laptop usage. See this link for Toshiba's keyboard troubleshooting: http://askiris.toshiba.com/ToshibaSupportSite/search.do?cmd=displayKC&docType=kc&externalId=639911xml&sliceId=&dialogID=45559243&stateId=0%200%2045557500
The link to the User's Guide is here for the A100/A105 product line. http://www.csd.toshiba.com/cgi-bin/tais/su/su_sc_docTOC.jsp?moid=1484725&rpn=PSAA8U&ct=UG&soid=1266386&BV_SessionID=@@@@0620704634.1214760254@@@@&BV_EngineID=ccccadeehkeldeecgfkceghdgngdgmn.0
The support home is at the link below, and you can choose your exact actual model from the drop down list (Satellite in the middle) on the far right. http://www.csd.toshiba.com/cgi-bin/tais/su/su_sc_modSel.jsp?BV_SessionID=@@@@0620704634.1214760254@@@@&BV_EngineID=ccccadeehkeldeecgfkceghdgngdgmn.0
There are a couple of basic concerns I have become aware of over the past few months, however, that you should be made aware of as well. First, there is a critical BIOS update for the A100 model, and failure to update could result in issues with your battery specifically and your PC generally. The link with the basic information, concerning a randomly chosen A100 model is at http://www.csd.toshiba.com/cgi-bin/tais/su/su_sc_supportNews.jsp?moid=1484720&rpn=PSAA8U&ct=SN&hideNav=true&sn_mod=1484720&sn_rpn=PSAA8U&sn_mpn=&BV_SessionID=@@@@0620704634.1214760254@@@@&BV_EngineID=ccccadeehkeldeecgfkceghdgngdgmn.0
[I do not know if the following impacted your situation, but if the battery was one of the bad ones, it could very well be the root cause.]
Basically, it was discovered that many batteries in the Toshiba models cited were defective and have created major issues - up to and including catching on fire!
So, you should check your battery to be certain that you are not at risk. If your battery is one of those indicated as defective, they will replace it free - and they are also very definite about not using the machine on AC with the battery installed... Please take a look at the link --
Finally, if you still believe that you must replace the keyboard on your notebook, you can purchase it from National Parts Depot, which is the company distributing for Toshiba. See link below, and I would suggest contacting them to ensure that diagram and/or instructional document is included.
If you need further assistance, please post back. Otherwise, thank you for using and rating FixYa!