WhatsApp for Samsung Galaxy Ace Plus S7500

The Ace Plus ships with Android 2.3 Gingerbread, and WhatsApp plus almost every current app dropped support for it years ago, so the Play Store either hides them or shows 'your device isn't compatible.' Your realistic option is to sideload an old APK version that still targets Android 2.3+. First enable Settings > Applications > Unknown sources (tick the checkbox), then open the downloaded .apk with a file manager to install it. Be aware that even old WhatsApp builds now refuse to verify your phone number because the registration servers reject the outdated client, so the chat apps that still work tend to be lightweight or self-hosted ones. See how others solved this on Reddit

Use an APK archive like APKMirror or the Internet Archive and sort through older versions of an app until you find one whose minimum requirement is Android 2.3.3 or lower, since anything needing 4.0+ will refuse to install. Download the .apk (the SD card is a handy place to keep it), enable Settings > Applications > Unknown sources, then tap the file in a file manager to install. Keep in mind that an app can install fine yet still fail to connect, because modern Google Play Services or TLS 1.2-only servers reject Gingerbread's networking stack. See how others solved this on Reddit

The current Facebook app needs a much newer Android version, so on 2.3.6 your best bets are to sideload an old build of Facebook Lite (older versions still target Gingerbread) or simply use the stripped-down mobile site at mbasic.facebook.com in the stock browser. To sideload, enable Settings > Applications > Unknown sources, then install the old APK from a file manager. If login fails because of outdated security certificates, fall back to mbasic.facebook.com, which has the lightest requirements and usually still loads. See how others solved this on Reddit

Android 2.3 only negotiates old TLS versions, so even an APK that installs cleanly often can't complete the secure handshake with today's servers, which is why logins and syncing fail. First check Settings > Date & time and make sure the clock is correct, because a wrong date makes every certificate look expired or invalid. Beyond that, prefer 'Lite' clients and basic mobile sites (like mbasic.facebook.com) that demand less from the connection; anything tied to current Google Play Services will generally still refuse to authenticate. See how others solved this on Reddit

Most mainstream apps now block old Android at the server level, so lightweight 'Lite' clients and mobile web pages are the dependable route on the Ace Plus. Stick to Facebook Lite or the mbasic site, use webmail in the browser instead of the Gmail app, and for chat look at older or self-hosted clients rather than current WhatsApp/Instagram builds. Sideload via Settings > Applications > Unknown sources and accept that any app depending on current Google Play Services will likely fail to authenticate. See how others solved this on Reddit