Help me reinstall Gapps in my Rooted Xperia SP

Recently, I rooted my Xperia SP (running on Stock Jellybean 4.3). Out of excitement, I uninstalled a few Google Apps (gapps) from my phone. But I think I require the Play Store. How can I **reinstall Gapps** on my phone? Let me clearly explain you my **current status →** for uninstalling those apps, I used ES File Manager (Root Explorer-->Uninstall System App). Though some apps like the play store, gmail, facebook etc. were uninstalled, I found that apps like google account manager, google backup transport cannot be completely uninstalled. So, now I have an incomplete set of Gapps. I compared this list of **essential** gapps with my file manager's system apps' list and found only SetupWizard.apk missing. So, I downloaded SetupWizard.apk from here and tried to install using ADB but I got this error: [INSTALL_PARSE_FAILED_NO_CERTIFICATES]. Another interesting thing is that when I try to install SetupWizard.apk using my file manager, I get these screens, out of which the **first screen suggests that Setup Wizard is already installed** in my phone. What the heck is all these, man??? Now, I am a total newbie to flashing and other super-geek things, so I am pretty scared to flash the gapps' zip using CWM. Please give me an alternative way, if possible.